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I have sendmail installed on CentOS 6 and whenever I try to send an email, it goes to spam on the recipient. (Gmail in this case)

OK, so, the domain I was to send mail on behalf of is: scalpello.info

The subdomain that is pointed to the ip of the server is: mail.scalpello.info.

The SPF / MX Records look like this: https://www.dropbox.com/s/4d1h8i8jvru8aap/Screenshot%202014-09-21%2015.26.34.png?dl=0

Here is a header from a test email that went to spam: http://pastebin.com/iuLUQPzc

Anyone have any ideas?

jeremys
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1 Answers1

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From your headers it appears that your server uses IPv6 to send email to the gmail server.

 Received: from scalpello.info ([2607:5300:100:200::693])

and you have not configured a reverse DNS record for your IPv6 address. And there is no forward IPv6 record for mail.scalpello.info either.

Additionally there's a lot of information in the Canonical question about legitimate email being classified as SPAM and preveting that here.

Community
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HBruijn
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  • Ok, how can I configure sendmail to use only IPv4? If I do that, will they not hit spam? – jeremys Sep 21 '14 at 13:56
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    The lacking reverse DNS records are an obvious reason for mail being rejected as spam, but that maybe not the only one :( No guarantees. – HBruijn Sep 21 '14 at 14:01
  • Hmm, ok then. My VPS provider does not allow me to set a reverse IPv6 address but I have changed the reverse IPv4 address to mail.scalpello.info. What do I do now? – jeremys Sep 21 '14 at 14:23
  • Far from the best solution, but I think you can force sendmail to use only IPv4 for sending e-mail with the setting `CLIENT_OPTIONS('Family=inet, Name=MTA')` in the sendmail.mc configuration file. – HBruijn Sep 22 '14 at 15:39