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When I check any of mailbox from my server with a tool like this one: https://www.port25.com/support/authentication-center/email-verification/ I get:

SPF check:          pass
DomainKeys check:   neutral
DKIM check:         pass
DKIM check:         pass
Sender-ID check:    pass
SpamAssassin check: ham

Seems OK.

My server IP is not blacklisted - I've checked it here: http://mxtoolbox.com/blacklists.aspx

All users in total do not send more than 50 emails a day. They're not spammers, just regular small business users.

Yet still there are problems with e-mail delivery to corporate addresses. Especially when I create a new domain, almost all e-mails from it will end up in spam. Or even worse: they are deleted without notice to sender or recipient.

Popular services like Gmail do not treat them as spam - problem is only with various corporate recipients.

What else should I check or do to put things right?

Marek
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1 Answers1

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eMail servers will drop your emails on corporate servers even without routing them to spam folders if you don't have correct reverse DNS record. Forward resolved IP should match reverse lookup for a email server responsible for all your domains(basically it is MX DNS record in your domains that point to your email server).

Just for example:

dig +short mail-lb0-f174.google.com a

returned IP : 209.85.217.174

nslookup 209.85.217.174

Returned PTR: 174.217.85.209.in-addr.arpa name = mail-lb0-f174.google.com

So, it match : DomainName <=> IP

You should send your email only through MX server that should be authorized for sending domains and match their SPF records. Probably you already have, but just in case, - email server should run only via static IP.

Usually corporate servers reply with rejection reason. Check your email logs, what error(s) numbers are they returned ?

Alex
  • 139