[Resolved] What does "550 Too many invalid recipients" mean?
...besides the obvious?
We were receiving the following error when our corporate mail server tried to send mail to any @shaw.ca address.
SMTP error from remote mail server after initial connection: host idcmail.shaw.ca [64.59.134.8]: 550 Too many invalid recipients
We checked the usual suspects - made sure we were not accidentally on any black list, checked to see if we had done any mass mailings recently (we hadn't) and triple-checked the spelling of the addresses we were sending to.
Hotmail and Gmail -> Shaw worked. Corporate mail server -> Hotmail and Gmail worked.
The problem went away while I was on hold with Shaw so we didn't get a chance to properly troubleshoot it. If anyone has some suggestions for what I should do next time, I would appreciate it.
Re: What does "550 Too many invalid recipients" mean?
Hey Mango,
Send me a message with your account number and i'll look into it. I'm not an expert with email related issues, but I can pass it on to one of my contacts
We have phone service with Shaw and our system was accidentally configured to send an autoresponse every time Shaw sent us an email with our voicemail. I corrected this and the problem seems to be resolved.
Thanks to Alex and Nathan for helping me track it down!
m. -- Dear Obihai, please fix the FXS to FXO Relay in the OBi110. Add this as your signature if you agree!
reply to Mango Some mail servers will temporarily black list a mail server's IP address if it send too many successive e-mails to unknown addresses in that domain. It's a way to prevent dictionary attacks where they keep hitting the mail server with different e-mail prefixes at that domain until one matches a real user. It tries every word in the dictionary until it gets a hit.
It's a way for spammers to validate or harvest e-mail addresses for spam lists or to hack an account. Somehow it thinks your e-mail server is messing with theirs.
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