Question : SMTP 5.7.1 error

I have a domain that occasionally gets  a #5.7.1 smtp;550 5.7.1 Unable to relay error.  The message looks like:

 


Since the error is referencing their server not mine would the issue be on their server?   I have been unable to identify any issues and we are receiving mail from all other domains however the issue is intermittent.  Occasionally they get a failur however their admin send about 15 test messages to me and other id's in our network last week.

Answer : SMTP 5.7.1 error

Hello Knance,

Yes it looks like a problem with their mail server. If it was yours then it would say something like 'mail.yourserver.com said #5.7.1...'.

Regards,
grblades