U.S. patent application number 13/220607 was filed with the patent office on 2011-12-22 for e-mail certification service.
This patent application is currently assigned to FIRST INFORMATION SYSTEMS, LLC. Invention is credited to Peter S. AVRITCH, Bruce M. CLAY, James R. DU MOLIN.
Application Number | 20110314283 13/220607 |
Document ID | / |
Family ID | 34749312 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110314283 |
Kind Code |
A1 |
AVRITCH; Peter S. ; et
al. |
December 22, 2011 |
E-MAIL CERTIFICATION SERVICE
Abstract
A method is provided to handle an electronic mail message such
that the receiver of the e-mail message can verify the integrity of
the message. A request is provided from a sender's side to a
service. The request includes information regarding the e-mail
message. The service processes at least a portion of the request to
generate a result. For example, the service may encrypt the portion
of the request, according to a public/private key encryption
scheme, to generate a digital signature as the result. The service
provides the result to the sender's side. At the sender's side, the
result is incorporated into the e-mail message and the
result-incorporated message is transmitted via an e-mail system. At
the receiver's side, the result-incorporated e-mail message is
processed to assess the integrity of the received e-mail
message.
Inventors: |
AVRITCH; Peter S.;
(Sausalito, CA) ; CLAY; Bruce M.; (Moorpark,
CA) ; DU MOLIN; James R.; (Belvedere, CA) |
Assignee: |
FIRST INFORMATION SYSTEMS,
LLC
Tiburon
CA
|
Family ID: |
34749312 |
Appl. No.: |
13/220607 |
Filed: |
August 29, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12632655 |
Dec 7, 2009 |
8032751 |
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13220607 |
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10749911 |
Dec 30, 2003 |
7653816 |
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12632655 |
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Current U.S.
Class: |
713/168 |
Current CPC
Class: |
H04L 51/00 20130101;
H04L 63/123 20130101; G06Q 10/107 20130101 |
Class at
Publication: |
713/168 |
International
Class: |
H04L 9/32 20060101
H04L009/32; G06F 15/16 20060101 G06F015/16 |
Claims
1. A computer-implemented method of operating a service to generate
a result for an electronic mail ("e-mail") message, comprising: by
the service, receiving a request comprising meta-data information
regarding the e-mail message, by the service, processing at least a
portion of the request to determine the result using a service
private key, the service private key kept secret by the service;
and by the service, providing the result for incorporation of the
result into the e-mail message prior to the e-mail message being
transmitted to a recipient of the e-mail message, as a
result-incorporated e-mail message, via an e-mail system.
2. The method of claim 1, wherein: the meta-data information
regarding the e-mail message includes at least an e-mail address of
a sender of the e-mail message.
3. The method of claim 1, wherein: the request further includes a
digest of a body of the e-mail message.
4. The method of claim 3, wherein: the digest of the body of the
e-mail message has been generated using an SHA algorithm.
5. The method of claim 1, wherein: the request does not include the
body of the e-mail message or information from which the body of
the e-mail message can be derived.
6. The method of claim 1, wherein: the service determines the
result to further include an indication of a level of certification
of the e-mail message.
7. The method of claim 1, wherein: the request further comprises
sender verification information; and the method further comprises,
by the service, processing the sender verification information.
8. The method of claim 1, wherein: a sender is associated with
e-mail message; and the method further comprises, by the service,
determining how the sender may be later located.
9. The method of claim 8, wherein: determining how the sender may
be later located includes associating a degree of certainty with
the determination.
10. The method of claim 9, wherein: the result includes an
indication of the degree of certainty.
11. The method of claim 10, wherein: a sender of the e-mail message
is associated with a particular e-mail address of a plurality of
e-mail addresses; and the method further comprises: at the service,
before providing the result for incorporation of the result into
the e-mail message, sending an inquiry e-mail message to the
particular e-mail address; and at the service, observing behavior
of the sender associated with the inquiry e-mail message.
12. The method of claim 11, wherein: the behavior of the sender
associated with the inquiry e-mail message includes the sender
sending an e-mail message to the service in reply to the inquiry
e-mail message.
13. The method of claim 11, wherein: the behavior of the sender
associated with the inquiry e-mail message includes following
instructions set forth in the inquiry e-mail message.
14. The method of claim 13, wherein: the instructions include
instruction to link to a particular universal resource locator.
15. The method of claim 1, further comprising: by the service,
before providing the result for incorporation into the e-mail
message, receiving a request for the sender to subscribe to the
service; by the service, sending an inquiry message to a sender
associated with the sender's side, by a transmission channel other
than the electronic mail system; and by the service, observing
behavior associated with the inquiry message.
16. A method for a recipient of an electronic mail ("e-mail")
message to validate a sender of the e-mail message, comprising:
receiving the e-mail message; processing a header field of the
received e-mail message using a public key of a service to generate
a first result; processing a portion of the received e-mail message
to generate a second result, the portion of the e-mail message
including at least metadata information regarding the received
e-mail message but not including the header field of message
processed to generate the first result; and comparing the first
result to the second result to assess the integrity of the received
e-mail message.
17. The method of claim 16, wherein: the metadata information
regarding the received e-mail message includes at least information
in a header field of the message configured to hold an e-mail
address of the sender of the received e-mail message.
18. The method of claim 16, wherein: the portion of the e-mail
message processed to generate the second result includes a body of
the received e-mail message.
19. The method of claim 16, wherein: the second result is a digest
of a body of the received e-mail message.
20. The method of claim 16, wherein: the step of processing the
received result-incorporated e-mail message to assess the integrity
of the e-mail message includes: deriving the portion of the request
from which the result was determined; processing the portion of the
request and the received e-mail message to assess the integrity of
the e-mail message.
21. The method of claim 20, wherein: deriving the portion of the
request from which the result was determined includes processing
the result using the service public key to generate a decrypted
result; processing the portion of the request and the received
e-mail message to assess the integrity of the e-mail message
includes generating a digest of the message body and processing the
generated digest and the decrypted result to assess the integrity
of the e-mail message.
22. The method of claim 16, wherein: the step of processing the
received result-incorporated e-mail message to assess the integrity
of the e-mail message includes processing the result to determine a
level of certification of the e-mail message.
23. The method of claim 16, wherein: processing the received
result-incorporated e-mail message to assess the integrity of the
e-mail message is without interacting with a service that created
the result, prior to the result having been incorporated into the
e-mail message.
24. The method of claim 16, further comprising: sending a request
to obtain contact information about the sender from a service that
created the result, prior to the result having been incorporated
into the e-mail message; and receiving the requested contact
information about the sender.
25. The method of claim 24, wherein: the requested contact
information about the sender is in a format appropriate to an
e-mail client program used by the recipient.
26. The method of claim 24, wherein: the requested contact
information includes at least one link to sender advertising.
27. A computing system configured to be usable by a recipient of an
electronic mail ("e-mail") message to validate a sender of the
e-mail message, the computing system configured to: receive the
e-mail message; process a header field of the received e-mail
message using a public key of a service to generate a first result;
process a portion of the received e-mail message to generate a
second result, the portion of the e-mail message including at least
metadata information regarding the received e-mail message but not
including the header field of message processed to generate the
first result; and compare the first result to the second result to
assess the integrity of the received e-mail message.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 12/632,655, filed Dec. 7, 2009, which is a
continuation of U.S. patent application Ser. No. 10/749,911 (now
U.S. Pat. No. 7,653,816) by Avritch et al., filed Dec. 30, 2003,
entitled "E-MAIL CERTIFICATION SERVICE." These applications are
incorporated herein by reference in their entirety for all
purposes.
BACKGROUND OF THE INVENTION
[0002] The present invention is in the field of electronic mail
and, more particularly, is directed to verification, by a receiver
of an e-mail message, of the integrity of the received e-mail
message.
[0003] Electronic mail has become a useful tool in our personal and
business lives. Unfortunately, like other useful technologies, it
has also become an intrusion. For example, only the most diligent
among us are able to avoid scurrilous attempts to sell us
nutritional supplements, mortgages, pornography and numerous other
"products." More recently, scammers have taken to using "spoof"
e-mails in an illegitimate attempt to gain access to our personal
information. For example, such scammers have spoofed BestBuy and
eBay, attempting to entice unsuspecting users into providing
personal information such as social security numbers and credit
card numbers. Thus, as useful as e-mail has proven to be in our
lives, it can be dangerous to blindly assume that received e-mail
is legitimate. However, efforts at minimizing intrusion of
technologies often unavoidably diminish the usefulness of the
technology whose intrusion we are seeking to minimize.
[0004] For example, "spam" catchers typically catch legitimate
e-mail messages in addition to spam e-mail messages. Users must
carefully scrutinize the caught e-mail messages, lest any of them
be legitimate and unintentionally ignored. Also, spoof e-mail
messages are more difficult to detect, as they appear in many
respects to be legitimate.
[0005] There have been a number of attempts to address the concerns
with e-mail. One notorious attempt is described in U.S. Pat. No.
5,999,967, to Sundsted. Sundsted has proposed attaching an
"electronic stamp" to each e-mail message sent, where the receiver
of the e-mail message receives money from the sender. The receiver
can determine whether it is "worth it" (from the value of the
attached stamp) to read the e-mail and receive the money. Because
Sundsted employs "stamps" having monetary value associated with
them, there is a practical requirement (which is difficult to
achieve) that the system to exchange value be secured against
fraud. Furthermore, even if the system to exchange value can be
made secure, there is nothing that allows a receiver of e-mail to
discriminate between senders from whom it is desirable to receive
e-mail and senders from who it is undesirable to receive e-mail
apart from the monetary benefit to the receiver who reads e-mail.
Perhaps even more significantly, nothing in the electronic stamp
allows one to assess the integrity of the e-mail.
[0006] In many respects, a proposed system known as "HashCash" is
similar to the system described in the Sundsted disclosure. The
proposed HashCash system is such that, before an e-mail message is
sent, a significant particular math computation must be performed
on the sending computer to generate a token. This computation is
such that, for example, it would take up to 15 seconds on a
standard 1 GHz PC. The token is incorporated into the e-mail
message. The receiving computer performs a relatively simple
computation to verify that the token is, in fact, the result of the
particular a math computation performed on the sending computer. A
drawback of HashCash, then, is that anyone who is willing to
undergo the computational burden can send e-mail messages
unimpeded. That is, like the system described in the Sundsted
patent, there is nothing in the token that allows the receiving
side to discriminate between senders from whom it is desirable to
receive e-mail and senders from whom it is undesirable to receive
e-mail, beyond verifying that the sender did, in fact, incur the
computational expense to generate the HashCash token. That is, in
some sense, HashCash merely substitutes computational expense for
the monetary expense of the Sundsted system (albeit there is money
or other value received by the e-mail recipient).
BRIEF SUMMARY OF THE INVENTION
[0007] A method is provided to handle an electronic mail message
such that the receiver of the e-mail message can verify the
integrity of the message. A request is provided from a sender's
side to a service. The request includes information regarding the
e-mail message. The service processes at least a portion of the
request to generate a result. For example, the service may encrypt
the portion of the request, according to a public/private key
encryption scheme, to generate a digital signature as the result.
The service provides the result to the sender's side.
[0008] At the sender's side, the result is incorporated into the
e-mail message and the result-incorporated message is transmitted
via an e-mail system. At the receiver's side, the
result-incorporated e-mail message is processed to assess the
integrity of the received e-mail message.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a flowchart illustrating a process in accordance
with an aspect of the invention;
[0010] FIG. 2 schematically illustrates the relationship between
various entities as the FIG. 1 method is executed;
[0011] FIG. 3 is a flowchart illustrating, in greater detail, a
portion of the FIG. 1 method that is executed at the receiver's
side.
[0012] FIG. 4 illustrates a portion of the FIG. 3 method where it
is determined if a received e-mail message is a result-incorporated
message and appropriate action is taken.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIG. 1 illustrates a broad aspect of a method/system to
handle an e-mail message such that a receiver of the e-mail message
can assess the integrity of the e-mail message. FIG. 2 illustrates
the architecture of the method/system. Referring to FIGS. 1 and 2,
a plurality of senders 102a through 102n (referred to generically
in FIG. 1 by the reference numeral 102) and a plurality of
receivers 106a through 106n (referred to generically in FIG. 1 by
the reference numeral 106) are, in a basic form, present in any
e-mail system. That is, any sender 102 can send an e-mail message
to any receiver 106 via the e-mail system 118.
[0014] Referring specifically to FIG. 1, at step 110, an e-mail is
created at the sender's side. For example, the user authors an
original e-mail message using standard e-mail client software
(e.g., Outlook 98 or Outlook 2000), including indicating a desired
recipient of the message. At step 112, information regarding the
e-mail is provided to the service 104. The user does not need to
take any special course of action to cause the information to be
provided to the service 104. The process is intentionally
"transparent" to the user to eliminate any possible confusion and
extra steps that might otherwise interfere with the rapid
deployment and use of the service 104.
[0015] For example, upon detecting an e-mail message to be sent,
programming code either embedded within the email client or
included as an add-on component intercepts the e-mail message. The
mail client interacts with the service 104, in the form of a single
TCP/IP request using a standard Internet protocol such as HTTP or
HTTPS. By using standard Internet protocols communication with the
service 104, packets of the communication will generally not be
blocked by corporate or home DSL firewalls. Packets transmitted by
HTTPS are also generally immune from network snooping since HTTPS
is a secure protocol. It is noted that payload data of HTTP
transmissions may be internally encrypted.
[0016] In one example, the information regarding the e-mail
message, provided to the service 104, includes the following
information:
Sender's email address Recipient's email address Digest of message
body (mathematical hash of the email text)
[0017] In general, the information regarding the e-mail message
includes information such that, after being processed by the
service 104 to generate a result, as discussed below, the
receiver's side 106 can process the result and assess the integrity
of the e-mail message.
[0018] In some embodiments, the information provided to the service
104 includes the sender's identity and authentication (typically
account/password). This information, as opposed to being
information regarding the e-mail message, can be characterized as
information about the sender, from which the service 104 can
authenticate the sender.
[0019] It is not necessary for the sender's side 102 to provide the
actual content (body) of the e-mail message to the service 104.
This contributes to maintaining the privacy, security and comfort
of the sending user. The e-mail message body is "hashed" by the
mail client at the sender's side 102 to derive a multi-digit
numerical sequence which represents the substance of the message
without disclosing its content. The hash result, more commonly
known as a message digest, is a mathematically unique number
generated according to the industry standard SHA-1 algorithm. The
theory of SHA-1 is that it will never generate the same message
digest for non-identical input text, yet it will always generate
the same digest for the identical input text. Message digests are
most commonly used in security schemes utilizing RSA encryption
systems and have been accepted by industry for many years as a very
dependable form of representing messages and for detecting
unauthorized changes to such messages. It is the message digest,
not the substance of the message itself, that is the information
regarding the e-mail message provided from the sender's side 102 to
the service 104.
[0020] Referring still to FIG. 1, at step 114, the service 104
processes the information regarding the e-mail to generate a
result. In particular, the information regarding the e-mail is
routed, using load-balancing techniques, to an appropriate HTTP
server of the service 104. A goal of load balancing is to reduce
load or bottlenecks and minimize risk due to system failures.
Off-the-shelf hardware contributes to this. Also, senders may be
"assigned" to particular groups, and the groups may be assigned to
sets of servers. In this instance, each sender will locally save
the URL/IP for its associated group and, thus, will be able to help
avoid traffic jams by going directly to a server that is able to
handle its requests. This load can be spread around the
country/world so the "whole universe" is not potentially trying to
simultaneously hit one single access point. Downtime is improved
since, if a server does go down, only its assigned group is
affected.
[0021] The service 104 executes a program to authenticate the
account name and password. In addition, the sender's e-mail
address, recipient's e-mail address and message body digest are
combined (e.g., concatenated) along with additional housekeeping
information (timestamp, sequence numbers, priority, sorting,
keywords, etc.) and provided as input to the industry-standard
SHA-1 algorithm, to form a 160-bit unique result. In some
embodiments, a portion of the 160-bit unique result is discarded in
order to increase performance and reduce the size of the result
without meaningfully degrading the ability of the receiving side
106 to adequately assess the integrity of the e-mail message.
[0022] Still at step 114, the service 104 signs the result (entire,
or a portion thereof as discussed above) of the SHA-1 algorithm
with a private key, such that it can be decoded using the
corresponding public key. The private key is kept secret by the
service 104, and the public key is made available to the receiver
side 106. In some embodiments, the public key is "embedded" within
the receiver side e-mail client software. The signing determines a
sequence result that is an alphanumeric sequence of characters
approximately 128 characters long. The service-determined sequence
result is returned from the service 104 to the requesting sender
102. In some embodiments, a corresponding result code is also
provided to the sender 102.
[0023] Further, in some embodiments, the service 104 performs a
variety of accounting, logging and account management procedures at
step 114 so that usage and quality of service can be monitored and
so that, for example, billing functions can be executed as
appropriate.
[0024] At step 116, the sender 102 incorporates the
service-determined sequence result into the e-mail message. In one
embodiment, the service-determined sequence result is incorporated
into the e-mail as an SMTP mail header. Mail headers are commonly
used within existing SMTP systems, and such systems include
processes to perform the routing and housekeeping out of view of
the users such that e-mail messages ultimately arrive in the inbox
of their intended recipients. Industry-standard guidelines cover
the use of such mail headers, so e-mail messages including the mail
headers are allowed to pass through the existing SMTP
infrastructure without being blocked, without interfering with the
quality of service delivered to users, and without being
altered.
[0025] Turning back to FIGS. 1 and 2, the result-incorporated
e-mail message is then transmitted via the e-mail system 118 to the
sender's SMTP server, and, ultimately is forwarded to the
designated recipient's POP3 email account. SMTP routing software
along the way is free to either ignore or interpret the SMTP mail
header holding the service-determined sequence result. Generally,
the SMTP mail header will be ignored (with the exception of the
SMTP server or e-mail client of the intended recipient).
[0026] The e-mail client software of some intended recipients may
not be "enabled" (either does not have the capability or is not so
configured) to process the SMTP mail header holding the
service-determined sequence result. The sender need not know (or
care) if the recipient is using enabled e-mail client software. If
the e-mail client software of the receiver is enabled, the SMTP
mail header holding the service-determined result will be
processed. Otherwise, non-enabled receiver clients ignore the SMTP
mail header, generally behaving as if the SMTP mail header was not
included in the received e-mail message at all.
[0027] If the e-mail client software of the recipient is enabled,
at the receiver side 106, the sequence result is processed at step
120 to assess the integrity of the received e-mail. The e-mail
message is received "normally" by the email client software from
the recipient's SMTP/POP3 server. Before presenting the incoming
e-mail message to the user, the e-mail message is preprocessed to
assess the integrity of the received e-mail message. This may be
accomplished by validation code that is, for example, embedded into
the e-mail client; a third-party add-on component to the email
client; integrated into an embedded or third-party anti-SPAM
product; integrated in whole or in part, or as an add-on, within an
advanced SMTP server such as Microsoft's Exchange Server.
[0028] FIG. 3 illustrates, in greater detail, processing of step
120 at the receiver side 106. Turning now to FIG. 3, upon
interception of the incoming message, at step 302, the validation
code generates a first SH-1 result, based on the body of the
received e-mail (the part the user generally sees). If the body of
the received e-mail has not changed since being composed by the
sender 102 (more properly, since the message digest was created at
step 112 of FIG. 1), then the SH-1 result, computed at the
receiver's side 106 in step 302, will be the same as the digest
computed at the sender's side 102 and provided to the service 104
at step 112.
[0029] At step 304, the first SH-1 result is concatenated with the
sender's and recipient's e-mail addresses as contained in the
received e-mail. This concatenation is the basis of a second SH-1
result generated at step 304. The second SH-1 result nominally
replicates the service-determined result (step 114 of FIG. 1)
computed by the service 104 and incorporated into the e-mail
message at the sender's side 102 (step 116 of FIG. 1).
[0030] Also at step 306, the public key associated with the service
104 is used to decode the service-determined result incorporated
into the received e-mail message, to determine a decoded
service-determined result. If there has not been spoofing or
hacking or other alteration of the e-mail message (whether willful
or otherwise), the decoded service-determined result matches the
second SH-1 result. Once the integrity of the received e-mail has
been assessed, appropriate action is taken. At step 4308, the
decoded service-determined result is compared to the second SH-1
result. If these are the same, then the received e-mail is "sound"
and appropriate action is taken at step 310. If these are not the
same, then the received e-mail is not "sound" and appropriate
action is taken at step 312.
[0031] In accordance with some embodiments, at the receiver's side
106, it is determined whether a received e-mail message is
identical to e-mail messages previously received. This is typically
a result of an identical e-mail message being sent to the recipient
repeatedly. Specifically, a cache is maintained at the receiver's
side 106 of service-determined results. By comparing the
service-determined result associated with a received e-mail message
to entries in the cache, it can be determined that the received
e-mail message is identical to one or more e-mail messages
previously received, and appropriate action can be taken.
[0032] In accordance with some embodiments, in addition to the
service-determined result, the SMTP message header includes
additional information provided at the sender side 102. For
example, this additional information may include keywords, which
can be used by the e-mail client software at the receiver's side
106. This additional information can be processed and appropriate
action taken. For example, the e-mail client software at the
receiver's side 106 may use the information for sorting of e-mail
messages or for otherwise controlling the placement of e-mail
messages in the e-mail inbox.
[0033] Referring to FIG. 4, it is recognized that some received
e-mail messages will not be result-incorporated e-mail messages. At
step 402, it is determined whether the received e-mail message is a
result-incorporated e-mail message. This may be accomplished, for
example, by checking for the appropriate SMTP header where the
result would be expected to have been incorporated into the e-mail
message. If the e-mail message is a result incorporated e-mail
message then, at step 404, processing takes place according to FIG.
3. Otherwise, at step 406, appropriate action is taken. For
example, preference may be to consider such unverifiable e-mail
messages to be of a low priority.
[0034] We now discuss how senders 102 may initially "register" with
the service 104. Generally, before the service 104 will transmit a
result to the sender's side 102, it must receiving an indication of
agreement by the sender to terms of use of the service. The
indication of agreement to terms of use of the service 104 may be
as a result of an initial subscription by the sender 102 to the
service. The sender's side is nominally associated with a
particular e-mail address of a plurality of e-mail addresses. At
the service, before transmitting the result to the sender's side,
an inquiry e-mail message may be sent to the particular e-mail
address, and the service may observe behavior of the sender
associated with the inquiry e-mail message. For example, the
expected behavior of the sender associated with the inquiry e-mail
message may include the sender sending an e-mail message to the
service in reply to the inquiry e-mail message. Additionally or
alternately, the behavior of the sender associated with the inquiry
e-mail message may include following instructions set forth in the
inquiry e-mail message, such as instructions to link to a
particular universal resource locator. The inquiry message may be
sent by a transmission channel other than the electronic mail
system. For example, the transmission channel may include a
hardcopy delivery service, such as a mail service or similar
courier service, and may even require signature of the sender.
[0035] In some embodiments of the e-mail client (at the receiver's
side 106) or included add-on component that intercepts the e-mail
message, facility is provided for the receiving users to use data
from the database of sender information associated with the service
104. For example, a button may be provided on the e-mail client of
the receiver that can be activated by the receiver while
viewing/selecting a result-incorporated message. As a result of
activating the button, a query is sent to the sender information
database for information on the sender. The sender information is
available for display to the recipient. The information could be
provided for display in text or rich formats, for example,
including XML, HTML, etc. The information could even include, for
example, a photograph of the sender if the photo was provided to
the service 104.
[0036] As another example, a facility (such as a one-click import
button) may be provided to add the sender to the contact list
associated with the recipient's e-mail client software (since
details about the sender like name, address, phone, e-mail
addresses, etc. are included in the sender information database).
Support may be provided in a format appropriate to the e-mail
client, such as vcards and or the richer format supported by
Outlook. (It is noted that Outlook 2003 has photo support). Links
may be even be provided to web sites. As an example of the
usefulness of such a facility, a real estate agent may send an
email to a local prospect, and the prospect could have confidence
as to the integrity of the information about the real estate agent,
as provided from the sender information database. This can be a
selling point for that real estate agent over other real estate
agents whose information is not available from a trusted
source.
[0037] While the present invention has been particularly described
with respect to the illustrated embodiments, it will be appreciated
that various alterations, modifications and adaptations may be
based on the present disclosure, and are intended to be within the
scope of the present invention. While the invention has been
described in connection with what are presently considered to be
the most practical and preferred embodiments, it is to be
understood that the present invention is not limited to the
disclosed embodiment but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the scope of the claims.
* * * * *