When I send to a specific address it is returned undelivered with ERROR 550. If I send from my ISP Server to same address it is delivered. What is the problem?
I have a PC with Windows 7 and run Mozilla Thunderbird. I have not made any H/W or S/W changes this year apart from normal Windows updates. The following problem started a week ago. When I send an email to a specific UK commercial address I immediately receive a reply "Undelivered Message Returned to Sender: ERROR 550 Message Rejected etc". If I send an email to the same UK commercial address from my Internet Service Provider's Webmail - it is delivered normally. If I send an email to the same UK commercial address from my Gmail account - it is delivered normally. Emails I send from Thunderbird to any other email addresses are delivered normally. I have discussed this problem with the IT support at the UK commercial address (where I have a problem) and they say everything is working normally with their email system. What do you think could be the problem?? ...Thanks
Alla svar (2)
Have you googled error 550?
This site: http://postmaster.comcast.net/smtp-error-codes.php shows how much of a catch-all it can be; the exact wording (instead of "Message Rejected etc") is probably essential to make sense of it.
On the whole it looks like an issue at the recipient's end, but given the cavalier approach to error messages taken by some email operators it might mean your message has been rejected by the server. It's possible that your ISP's IP address range has been blacklisted, but other routes, via webmail or other services will use different servers with different addresses and so evade the blacklist.
Thanks for your views - I am fairly new to Thunderbird so have not had much experience of rejected emails and associated error codes. I will follow up your points. ...Thanks