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Mango
What router are you using?
Premium
join:2008-12-25
www.toao.net
kudos:13
Reviews:
·Callcentric
·Anveo
·Shaw

2 edits

[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.

Thanks,
Mango


Shaw_Alex
Official Shaw Rep

join:2010-12-16
kudos:1

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

-Alex

Expand your moderator at work

Mango
What router are you using?
Premium
join:2008-12-25
www.toao.net
kudos:13
reply to Shaw_Alex

Re: What does "550 Too many invalid recipients" mean?

Thank you.


Mango
What router are you using?
Premium
join:2008-12-25
www.toao.net
kudos:13
Reviews:
·Callcentric
·Anveo
·Shaw

The verdict: I'm guilty.

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!


8744675

join:2000-10-10
Decatur, GA

1 recommendation

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.