Emails to a plus.net recipient rejected with 552 Spam Message Rejected

[#1]

Hi there

I'm actually posting as an email sender and not currently a plus.net customer ourselves (our options remain open!) but we're having trouble getting emails through to a customer who is hosted by plus.net and uses your MX servers.  They are bouncing back as follows:

[redacted]@[redacted].f9.co.uk
mx.avasin.plus.net
Remote Server returned 'mx.avasin.plus.net #5.0.0 smtp; 552 Spam Message Rejected'

(Customer email address redacted for their privacy)

Our emails are coming from marl.co.uk

I had been made aware that the A-record (web host) for marl.co.uk was blacklisted under UCEPROTECT L3, and have resolved the issue as marl.co.uk now points to CloudFlare which is clean, and marl.co.uk no longer appears under any blacklist search I've tried.  This has been the case for almost 2 weeks.

However, plus.net MX servers continue to reject our email as spam.  I somehow got 2 to go through but it appears to be random.  I thought it may be the message content (fairly lengthy email signature) but have tried completely disabling the signature and sending a plain test email, to no avail.

How can we get this cleared up?

Many thanks

IT Dept
Marl International

[#2 · Accepted solution]

Thanks for your post @derykmarl and welcome to our Community Forums

Could you drop me a private message by going Here with the full unredacted bounceback, and a sample (headers) of the email that gets rejected? I'll then raise this with our network infrastructure operations team for further investigation.

Cheers

[#3]

Emails going through now thanks to the excellent wizardry from Gandalf.  Much appreciated

[#4]

Cheers for the post back @derykmarl 

No problem at all, I'm happy to have helped solve this for you. ‌‌

Let me know if there are further issues or anything else you'd need help with.