The server responded: 550 <****>sender rejected (blacklisted by local policy)’

[#1]

Hello. I have an issue that might not be related to other threads referring to code 550.

I have an email address hosted elsewhere.  I can receive emails ok (from their pop server).  Until yesterday I could send using relay.plus.net.  Now I get the message below.

Task ’email@mcchoir.org.uk - Sending’ reported error (0x800CCC78) : ’Cannot send the message. Verify the email address in your account properties.  The server responded: 550 <email@mcchoir.org.uk> sender rejected (blacklisted by local policy)’

The email address does not appear to be blocked according to mxtoolbox.

I have several email addresses (exchange, gmail, plusnet) and all these are receiving and sending normally.

I use outlook client (classic) on windows 11

I have tried recreating the account but can't get past the "test account settings", with the same error.

I have tried without and with outgoing smtp authentication.  Using my username, something@username.plus.com, username+something.

Thanks for any advice you can give.

[#2]

Hi @zetlandpaul 

Thanks for coming back to the community. 

I'd recommend running a virus/malware scan on your device and updating your password. Once you have done this and if you still have the same error, please send me a private message with a screenshot of the error message/non-delivery report and the email address affected and we will help you further.

Speak to you soon

Leanne.

[#3]

Having seen your screen shots in the image moderation queue gives rise to the question of why are you sending emails for an external email host via Plusnet’s SMTP rather that the provider’s SMTP?

The SPF configuration refers to MAAF not Plusnet - is this a Plusnet or a MAAF account you are trying to bounce through?

The error message suggests that the account has been compromised.  Did you change the password and do the virus scan?  The account will need to be taken out of quarantine.

[#4]

I have being sending via the plusnet relay for about 10 years without issue. 

I was advised to include include:madasafish.com  in the domains spf record.  Either I was wrongly advised or I misunderstood the instruction.   I have taken that out and replaced it with include:_spf-internal.plus.net include:_spf-internal2.plus.net. 

(I no longer have a record of this advice)

The reason I use the plusnet relay is that it allows a greater number of bcc addresses than the external host server which is limited to 50.  I need around 250. 

The account password is irrelevant.   I have created a new mailbox, relay@, for testing and that works ok (pop delivery and relay send) but fails if I try to use the relay@ credentials to send from email@mchoir.org.uk.   However I have found that if I do "a send on behalf of " it does work. E.g. relay@paulandjune.plus.com; on behalf of; email@mcchoir.org.uk

 I'm now looking for other solutions for bulk mail (not that 250 is bulk by commercial standards).