Some of my Email users are sending Emails to outside and they are getting error 550-Message rejected because ( []:41643 is 550 blacklisted. (in reply to RCPT TO command). But when I check all blacklist websites the IP is not black listed and the reputation is good. What is the reason of this error. And how can i resolve this.



Howdy -- yeah, I don't see your IP address listed on any of the common blacklists.

There's a variety of reasons why a mail server may not accept email though -- and while we certainly don't advocate this, some of those are even due to the country of origin.

Since your server isn't listed on any blacklists, the only way to determine why email from your server is being rejected is to contact the administrators of the mail server that's rejecting your email.