I have a zimbra installed and working fine. The main domain is mbox.dominiocorp.com.br (fictitious).. I have SPF, DKIM, _dmarc, reverse configured and tested. The emails of the domain mbox.dominiocorp.com.br enter the inbox. I added two more domains on top of this zimbra (dominiocorp3.com.br and dominiocorp4.com.br). Both have been configured their SPF, DKIM, _dmarc and the reverse of these domains is the IP of the domain mbox.dominiocorp.com.br. All emails from new domains, are going to the box SPAM of gmail, yahoo, hotmail. I see in the original message that SPF and DKIM are correct, without errors.

dig -t txt mbox.domaincorp.com.br

mbox.domaincorp.com.br. 300 IN TXT "v=spf1 mx ip4: -all"

dig -t txt domaincorp3.com.br

domaincorp3.com.br. 84600 IN TXT "v=spf1 a mx ip4: ~all"

dig -t mx domaincorp3.com.br

domaincorp3.com.br. 84600 IN MX 5 mbox.domaincorp.com.br.

dig -t mx mbox.domaincorp.com.br

mbox.domaincorp.com.br. 84600 IN MX 5 mbox.domaincorp.com.br.

host mbox.domaincorp.com.br

mbox.domaincorp.com.br has address mbox.domaincorp.com.br mail is handled by 1 mbox.domaincorp.com.br.

host domaincorp3.com.br

domaincorp3.com.br has address domaincorp3.com.br mail is handled by 10 mail.domaincorp3.com.br.

host domain name pointer mbox.domaincorp.com.br

Could anyone tell me what might be happening? Is it any configuration due to IP being shared? Or any add-on settings that I need to perform on zimbra?

I've read that the zimbra antispam itself might be punctuating this domain as bad. Does it proceed? By sending an email to check-auth@verifier.port25.com I received the result below.

Here's a link with the original header and the answer from check-auth@verifier.port25.com


  • Do you see any errors in the mail log from any large email providers, and is your server IP or domain blacklisted by any RBLs (try mxtoolbox.com). – Simon Greenwood Dec 8 '17 at 20:42
  • Thanks for the feedback. I've already looked at the RBLs, the only one I'm listed on is spamrats.com. I can not find any errors in the zimbra server logs. Gmail has a very good filter. And for new domains, if you have donfigured dkim, spf, reverse it does not mark as spam. there must be something wrong in my settings. – Christovam Dec 9 '17 at 17:20
  • Logs send gmail. docs.google.com/document/d/… – Christovam Dec 9 '17 at 17:21
  • We're tending to find that any RBL listing should be dealt with to ensure mail delivery, and new domains actually have a low reputation until they can be proved. There are situations where Zimbra will silently drop mails: one I found was if two mails are sent with the same ID, but that was an artifact of a system I was receiving mail from. In the setup stage it's better to see spam to deal with any issues so I would advise configuring Zimbra to send spam to a mailbox or folder for training if you think that's the issue. – Simon Greenwood Dec 10 '17 at 8:12
  • Hi! I have already requested removal of the spamrats list. I suspect of a low reputation, but if I set up domaincorp3.com domain on a new server (only that domain on the server) the email goes to the inbox. But on a server that has multiple domains going to spam. I think one of the reasons is helo. The helo of domaincorp3.com is the helo of domaincorp.com. I understand that this should not influence, so it is a hypothesis. I did not quite understand Simon, you commented on the zimbra sending the emails to a spam box or trainings. The emails I send from zimbra to other domains go to spam. – Christovam Dec 11 '17 at 11:34

It is becoming increasingly difficult to establish and maintain reputation for standalone mail servers when dealing with the large mail providers. Among the things you have to consider are whether your server, or IP address or indeed netblock are on RBLs, which can be a legacy issue from previous users of the address. Also ensure that your configuration matches your IP address, particularly that your HELO address resolves to the sending IP address. Zimbra itself can be hard to debug for inbound mail so turn on logging in the setup stage.

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