I have a postfix mail server for our firm. The mails sent from this server to gmail and yahoo goes in spam.

The postfix is configured on our server and it has never been used for spamming.

Everything is configured as is should. The server works fine, the headers are as they should be.

What should I do in order the messages not to go in spam?


Take this Email Server Test and it will tell you what you can do to deliver your emails cleanly.

Email Server Test

Welcome to the Email Server test page.

This page does a check of your Outgoing Email Server to see how the Email server fares with respect to some of the “best practices”.

If you are facing issues where your outgoing Emails are consistently rejected by other servers or land up in Junk Email or SPAM folders of the recipient mail box, this test can help you in identifying the problems.

Some of the technologies/RFC Compliance your Email server is tested for are:

HELO Greeting
Reverse DNS
Domain Keys
SPAMAssassin Content Checks
BATV (Bounce Address Tag Validation)

Testing Process

1. Send an Email to Test Email Address test@allaboutspam.com
2. That email will bounce with a URL in the bounce messge.
3. Either click on the URL or Copy/paste the URL in a browser.
4. You will see report on your Email Server.

If you do find the report useful, please feel free to drop a note of appreciation. The Email server test report will be available in this page.

  • all about spam is greylisted.
    – Chris
    Aug 6 '21 at 20:54

Check the headers of the email received by GMail and Yahoo accounts for hints as to why they are being marked as spam.

As Berkay said, it could be SPF-related; the headers should show this, e.g.

Authentication-Results: mx.google.com; spf=pass 
(google.com: domain of abc@xyz.org.uk designates 
xxx.xxx.xxx.xxx as permitted sender)

It doesn't sound like you're blacklisted, else other domains would have issues with your email, but DNSBL can be used to check your IP if you need to.

The article that itsadok linked to gives a good overview of things to check.

  • +1 as you mentioned how to check for SPF related headers. This has been the most frequent cause mail sent via my mailserver ending up in the spam folder.
    – dunxd
    Apr 30 '10 at 10:35

Jeff recently published a blog entry on Coding Horror called So You'd Like To Send Some Email (Through Code). This has quite a number of good tips for what you can do to make your sending email more acceptable to external services.


Just to be safe, check your mx entries and check if you are blacklisted. http://www.mxtoolbox.com/


it can be due to the failing of SPF checks. read here to get information about SPF( Sender Policy Framework)


You may want to read this blog entry : "Postfix with DKIM, Domainkeys, SPf and Sender-ID" at http://www.tai.ro/2010/04/03/postfix-with-dkim-domainkeys-spf-and-sender-id/


This article has a great list of thing you should check. Its main points:

  1. Don't send spam
  2. Remove Your Server From Spamhaus’s Blocklists
  3. Configure Reverse DNS Lookups
  4. Format Messages Properly
  5. Create SPF Records
  6. Send All Messages From the Same Address
  7. Sign Email With DomainKeys or DKIM
  8. Use ‘Precedence: bulk’ for Bulk Emails?

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