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Having some problems with mail messages which are rejected as spam when sent directly to a user at a certain company address but if that users sends us a message and we reply, it is accepted. If I try connecting via smtp on command line from our server, the connection is received. Any ideas why a direct message is rejected as spam?

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marked as duplicate by Greg Askew, growse, voretaq7 May 22 '13 at 18:15

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You need to ask the admin of that company, no one here can say what they're running or what policies they have in place. –  NickW May 22 '13 at 15:47
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1 Answer 1

Quite a few spam filtering systems rank incoming e-mail lower if it references e-mail that was send from the receiving organization. The replying party adds a In-Reply-To: header referencing the original e-mail to the message. A quick lookup verifies the reference and mail gets through.

Your original e-mail is probably marked as spam for one or more of the most common reasons:

  • Forward/Reverse DNS and HELO/EHLO improperly configured
  • SPF record wrong/missing/etc
  • IP Reputation (DBSBL, SenderScore, and similar)
  • Your sending spam (or something that look a lot like spam)
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