Question Mail delivery failed: returning message to sender

When someone posts to a forum category Kunena sends the notification emails out to the subscribers but the emails dont arrive to Gmail users, this is the header response:

Action: failed
Final-Recipient: rfc822;XXXXXXX@xmail dot com
Status: 5.0.0
Remote-MTA: dns;
Diagnostic-Code: smtp; 550-5.7.1 This message is not RFC 5322 compliant, the issue is:
 550-5.7.1 duplicate To headers. To reduce the amount of spam sent to Gmail,
 550-5.7.1 this message has been blocked. Please review
 550 5.7.1  RFC 5322 specifications for more information. r14-20020a5d494e000000b0022efd79c5c1si2953902wrs.603 - gsmtp

SPF and DKIM are correctly setup for the account but i assume maybe there would be an extra SPF setting for gmail? I have googled it to death but cant find anything i understand, has anyone else had this issue and fixed it please?



 

Maybe this is helpful, but maybe you have already read this.
support.google.com/mail/thread/6700746/e...-we-are-compli?hl=en
support.google.com/mail/thread/6657150?hl=en
community.mimecast.com/s/article/Connect...l-Delivery-731048977

Yes i have checked these thanks, they refer to a different error "From' header is missing" as mine is about " 550-5.7.1 duplicate To headers."
I will post to Gmail help and see if i can get anywhere there.
thanks
 

Can you let us know if you get any solution to this please?  I'm getting the same error.
Thanks

Yep if i finjd the answer i will but nothing yet just returned mail and lots of it !

My ISP treats emails from LinkedIn forwarded from Google the same way. (I also had my ISP bouncing messages from the police.) The issue is usually that the recipient's ISP recognises it as likely to be SPAM, etc, and rejects it accordingly. This is frequently due to the host, or the IP address it uses for outgoing mail, as having been used for SPAM. Occasionally it will be the route it takes, often just one or a couple of IP addresses, is known for spamming. This latter one is usually seen when some mail goes and other is bounced. Checked the rejected mail (headers) to see what route it has taken.

BTW I assume blacklists have been checked.

Yes no blacklist issues and mail-tester.com reports 10/10 for this domain when sending email so everything is as right as it can be.

it is just when Kunena sends a bunch of emails to category subscribers that the gmail ones get rejected - all the other seem to get through.

This has been going on for weeks i cant find an answer to if anyone else has the same issue maybe it is a Kunena issue?

Unfortunately I don't know which Kunena version you are using, but in Kunena 6.0.4 some mail problems have been fixed.

thanks - i am using 5.2.5.
My hosts have eventually decided that it is the mail headers sent out by the forum that are not RFC5322 compliant which Google enforces.
i will have a look at Kunena 6 - is that a simple upgrade from 5 on Joomla 3?

Upgrading should not be a problem, but I recommend try it with a clone on a test site first.
docs.kunena.org/en/basics/upgrade/upgrade-k6-0