Outgoing email wrongly marked as spam


#1

On a BigV server I run email for a charity event (https://www.echtrees.org.uk). Outgoing email is very low - say 10 - 20 per day. 4 or 5 times a year we send out mailshots to approx 8,000 supporters. It looks as if a large proportion of these are marked as spam by the large email providers. It is likely that this is causing us to lose funds for the charity.

We suspect that the cause of this is that the mail providers see the sudden volume increase as suspicious. We do try to meet the recommendations such as SPF, DKIM, DMARC.

Can anyone suggest a way out of this?

Regards

Tony


#2

One thing we’ve noticed a few times recently is Gmail rejecting mail sent on IPv6 connections. In each case, there’s been no SPF record relating to that IPv6 connection, because there was no AAAA record for the sender domain. “A” in SPF implies “AAAA”, so simply creating an AAAA record for the sender domain pointing to the sending IP address might help.

Otherwise, take a good look at /var/log/exim4/mainlog to see what the error messages are. If you can’t work it out, say here what your sender address is, and post the error messages. Do obfuscate the left hand side of any email address, but not the domain.


#3

Google’s Bulk Sender Guidelines are well worth a read.


#4

As far as I can tell my DNS, SPF, DKIM, DMARC are all OK & tested. I have tried to follow the guidelines provided by the big providers.

I get no errors in logs. Messages are accepted and then either routed to spam folders or not delivered at all.

I’m fairly sure its all down to the sudden peak in volume which is not something I can do anything about.

The domain is echtrees.org.uk

Regards

Tony


#5

Presumably, much could also be down to users hitting the junk button.

It still sounds like it’s worth checking the ipv6 rdns, e.g., google’s additional ipv6 guidline:

If the sudden increase in volume is the trigger, enabling rate-limiting might be the way to go. I’ve not seen it in action (on exim4 / symbiosis) and I’m assuming it’ll gracefully queue rather than bounce.


#6

If you’re not 100% sure, or even want confirmation, then http://mail-tester.com/ is a great site for testing your outgoing mail.