Email error 553 - can't send emails

[jcs100]

I'm receiving the following error message on trying to send several emails from btinternet.com account today none with any content issues I can see.  Can someone advise solutions to resolve?  I've using web to access account and tried switching wifi connection to no avail.

 Sorry your email could not be delivered due to content policy reasons. Please check your message content for URLs, content and subject matter that could be construed as Malware, Spam or Phishing before retrying. (6-1-3-1) ID (6139417C44BC42DD) [Err code: 553]

[NeilO]

Hi @jcs100 welcome to the community and thanks for posting, I'm sorry to see you're getting a 553 error when sending emails. Are you using a public wifi connection or VPN?

I'd also recommend trying to change the subject matter to see if that helps.

Thanks

Neil

[jcs100]

Many thanks for the reply.  I've tried changing subject matter.  Using home wifi - tried changing to phone hotspot to see if that helped but no change.

[NeilO]

Hi@jcs100 are there any links or attachments included in the email?

Neil

[jcs100]

No - I was replying to emails in both instances, deleted the previous email text then tried to send via an entirely new email and neither approach worked.  

[NeilO · Accepted solution]

Hi @jcs100 Thanks for getting back to me. One last thing to try if you don't mind would be to turn off your router for 15 mins to try and get a different IP address. These are recycled and it's possible the one assigned to you may be blocked if it was previously used by a spammer.

Thanks

Neil

[JohnC2]

Hi @jcs100, did the advice from @NeilO  help?

Cheers

John

[HeskethPark]

No,
I tried turning of the router but made no difference.