The "short answer" is YES, because many ISPs now block when the SENT FROM e-mail address and REPLY TO e-mail address do not match. The SENT FROM and REPLY TO e-mail addresses must match because they are now checked as part of ANTISPAM measures.
If the COMCAST Internet network sees headers in e-mail which contain different SENT FROM and REPLY TO e-mail addresses, they now completely block delivery of the message in the NETWORK - it never makes it to the receiving MX server. No notice is given to either the sender or intended recipient - the message is simply sent to the circular bit bucket file.
SmarterMail also introduced this filtering capability in version 14.X, The setting is located under SETTINGS ===> PROTOCOL SETTINGS ===> SMTP IN, where REQUIRED AUTH MATCH can be set to:
- NONE - least restrictive
- EMAIL ADDRESS - most restrictive, both addresses must EXACTLY match
- DOMAIN - partially restrictive: domain must match, but sender can be different, so long as sender is valid within the domain name.
We have seen a lot of mis-matched SENT FROM / REPLY TO header entries from forms which are generated by websites and shopping carts. These require a lot of new coding on the part of the web designers to correct, but many of those same websites and shopping carts are still configured to NOT use SMTP authentication and like Comcast, YAHOO!, GMAIL, and OUTLOOK, we now check for SMTP AUTHENTICATION and BLOCK any messages which are not properly SMTP authenticated.
So, having digressed slightly, there are two things which we always enforce:
SENT FROM / REPLY TO e-mail address MATCH - EXACT MATCH, and
If someone's e-mail does not meet both of those tests, it is unceremoniously blocked.
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