Gmail is rejecting some forwarded spam messages -- instead of sending them to my spam folder -- which is causing problems with my forwarding account. (I'm using Zoho to forward emails from my domain to Gmail).

I keep receiving messages like these from mailer-daemon@mail.zoho.com:

The following message could not be forwarded to ******@gmail.com for *******@*********.net
Technical details of the failure:
5.7.1 [ 19] Our system has detected that this message is
5.7.1 likely suspicious due to the very low reputation of the sending
5.7.1 domain. To best protect our users from spam, the message has been
5.7.1 blocked. Please visit
5.7.1 https://support.google.com/mail/answer/188131 for more information. l12-v6si1431505oth.95 - gsmtp

----- Transcript of session follows -----

Received:from mail.freeusads.us ( []) by mx.zohomail.com
with SMTP id 1522285579869933.9255773736019; Wed, 28 Mar 2018 18:06:19 -0700 (PDT)
Date:Wed, 28 Mar 2018 15:51:08 -0400
From:"Personal Loan Pro" <personal_loan_pro@freeusads.us>
Subject:Want to streamline your bills into one, easy monthly payment?

P.S: Please note that your email forwarding will be disabled if there are too many failures.

The Google support link seems to be saying that the message was identified as spam (which is correct) but that instead of sending it to the spam folder, Gmail didn't deliver it at all. Zoho then sees this as a delivery failure, and will disable forwarding if there are too many.

What setting in Gmail do I need to change to stop this problem from occurring?

  • Blocking spam is normal. I would rather try checking zoho settings/support for not treating it as a problem. – reducing activity Sep 6 '18 at 4:59
  • 1
    @MateuszKonieczny Blocking spam thus is not normal. Heuristic spam filters are nowhere mentioned in [tools.ietf.org/html/rfc5322](RFC 5322] or [tools.ietf.org/html/rfc5321](5321). GMail therefore is not an email service, unless its spam filters can be disabled. Zoho is correct to implement mail delivery according to RFC; GMail is incorrect to have spam filters that cannot be disabled. Hope that makes the question clearer. Thanks – jcarpenter2 Sep 6 '18 at 14:22

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