Gmail spam flagging

Maintenance
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My domains are not new and many mails have been send to gmail and whitelisted (by saving the contact in gmail), yet persistently google dumps our mails into spam.

I have now found their postmaster tool and added our domains and validated them. When I run the troubleshooting process they provide, the give this list that our mail should adhere to

Confirm that you:

  • Sign messages with DKIM. Gmail doesn’t authenticate messages signed with keys that use fewer than 1,024 bits.
  • Aren’t using the DKIM length tag (l=) in message headers. This tag makes messages vulnerable to spoofing.
  • Publish an SPF record.
  • Publish a DMARC policy.

The DKIM length tag is the only one that is unclear to me. The rest are there.

Can someone help me with this? Does MiaB do this as part of the default setup?

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Mail-in-a-Box does all those things. Another thing that is important is that you set PTR correctly for both IPv4 and IPv6 addresses.

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Gmail is warning you about the optional DKIM l= (length) tag, which signs only part of the message body; that leaves the rest of the body unsigned and vulnerable to modification, so large providers now treat messages with l= as weaker or even effectively unsigned. To check whether this affects you, look at a raw message header in Gmail and inspect the DKIM-Signature line: if there is no l= tag, you can ignore that bullet; if it is present, you’ll need to ask your mail software or provider to regenerate your DKIM keys and signatures without l= and keep SPF and DMARC in place as Gmail recommends.

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That is not applicable to Mail-in-a-Box

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