550.5.7.1 Unable to relay

[jonny75904]

Hey guys,

One of my web projects here at work has started throwing this error when accessed externally. I cannot recreate the cause of this here at work. They lock us developers out of the server room so I can't see anything that goes on within the server either, and our server admin guy stays super busy.

Our client has not specified if this is a consistent phenomenon or not, and this happens when the website sends an email using the Mail.MailMessage object.

Also, occasionally it throws a CDO Message Object error, which I have no clue what causes that.

 

[giadich]

This error is normally thrown when SMTP mail failed to relay the message through another server.

Although I have seen in a rare occasion, CISCO PIX firewall blocked certain message if SMTP filtering was enabled. You might want to take a look there too.