I'm seeing a bunch of email with nothing in the FROM: field, just a yahoo "reply-to" field. These messages are received by my server, have an invalid "TO" field, so my server sends a bounce message to the "reply-to" field...
As a result, I'm getting on yahoo's "blacklist" for sending junk to them!
Is there any way to simply block messages which have an invalid "FROM" field? or is this something I wouldn't want to do? Is there a better way to resolve this?
Why should my zimbra server be accepting email with an invalid FROM: field anyway? (although there's probably no sanity or reliability tests done on the from field anyway..)
Basically as far as I can tell, someone is using this as a denial of service attack against me to get block me with yahoo...?
Thanks in advance!