Fixing My MTA’s Poor Reputation

emailemail-serverpostfixsmtpspam

I have a web site that needs to send email to customers to deliver files that they have purchased. Reliable email delivery is vital to this business. Unfortunately, most of the emails sent by my server are not delivered due to my MTA's "poor reputation." Here are some sample lines from my mail.log:

Feb 20 02:40:41 servername postfix/smtp[14580]: 4E30B1100C7: host aspmx.l.google.com[209.85.211.78] said: 421-4.7.0 [174.143.183.26] Our system has detected an unusual amount of 421-4.7.0 unsolicited mail originating from your IP address. To protect our 421-4.7.0 users from spam, mail sent from your IP address has been temporarily 421-4.7.0 blocked. Please visit http://www.google.com/mail/help/bulk_mail.html 421 4.7.0 to review our Bulk Email Senders Guidelines. 10si1216690ywh.92 (in reply to end of DATA command)

Feb 20 12:49:22 servername postfix/smtp[5651]: A86CB1CC0CF: to=<user@domain.com>, relay=mx3.comcast.net[76.96.58.14]:25, delay=55186, delays=55185/0.01/0.93/0, dsn=4.0.0, status=deferred (host mx3.comcast.net[76.96.58.14] refused to talk to me: 554 imta36.westchester.pa.mail.comcast.net comcast 174.143.206.168 found on one or more DNSBLs, see http://help.comcast.net/content/faq/BL000001)

Feb 16 10:50:11 servername postfix/smtp[6931]: 98B94380A1: host mx-in-2.webreus.nl[212.61.252.240] refused to talk to me: 554-mx-in-2.webreus.nl 554-Your access to this mail system has been rejected due to the sending MTA's poor reputation. If you believe that this failure is in error, please contact the intended recipient via alternate means. 554 More information can be found on http://senderbase.org/senderbase_queries/detailhost?search_string=174.143.206.168

Feb 16 10:50:12 servername postfix/smtp[6931]: 98B94380A1: to=<user@domain.com>, relay=mx-in-1.webreus.nl[212.61.10.240]:25, delay=173653, delays=173650/0.22/2.8/0, dsn=4.0.0, status=deferred (host mx-in-1.webreus.nl[212.61.10.240] refused to talk to me: 554-mx-in-1.webreus.nl 554-Your access to this mail system has been rejected due to the sending MTA's poor reputation. If you believe that this failure is in error, please contact the intended recipient via alternate means. 554 More information can be found on http://senderbase.org/senderbase_queries/detailhost?search_string=174.143.206.168)

Steps I've taken to try to improve the situation:

  • set up reverse DNS lookups to work correctly
  • set up SPF records for my domain
  • disallow incoming connections to my SMTP server
  • format messages according to RFC 2822
  • never send unsolicited messages (I never have)

My server is in Rackspace's cloud. Is it possible that the IP address's bad reputation was inherited from a previous customer? Some of the above steps have been taken in the past week–am I going to have to wait for the situation to improve? Are there other things I should be doing? Should I hire a third party to send emails for me?

Best Answer

Unfortunately the IP is blacklisted irrespective of the hardware that sits behind it, so there's not a lot you can do about your existing reputation except ensuring you are sending mail correctly and contacting the relevant spam lists. You may have to wait a few days or weeks for the situation to improve.

I would recommend using Google Apps for SMTP to eradicate these problems :)

Otherwise, if you keep going on your own, check:

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