550 #5.1.8 Domain of sender address does not exist

[#1]

Good Evening,

I am an owner of a small business and I am having difficulties sending emails to plusnet users.

The error is below - I have checked my MX, CNAME A and other email records and I cannot see any issue with them. 

I am not a plusnet customer myself, but this issue has me concerned enough for my customers as they are not receiving any order emails, and I have no other means to contact them which comply with GDPR. 

Any assistance is appreciated.

Kind Regards,

Steve

My Domain: hardyshobbies.co.uk

Error Message:

  BLANKED@care4free.net

    host mx-ironport.core.plus.net [212.159.9.200]

    SMTP error from remote mail server after MAIL FROM:<management@hardyshobbies.co.uk> SIZE=5625:

    550 #5.1.8 Domain of sender address <management@hardyshobbies.co.uk> does not exist

[#2]

Your message has been ignored but plus net are aware of this issue as you can see in this long thread:

https://community.plus.net/t5/Email/Plusnet-Email-servers-giving-random-SMTP-550-errors-for-inbound/...

[#3]

Hi Steve.

Apologies for the delayed response and thanks for reaching out to us here.

Unfortunately as @maidbloke has said it's something we're aware of and working to fix.

Please accept my apologies for the inconvenience caused in the interim.