Hi, First, sorry for the subject's name. No idea else than that :-) My problem is simple. On my Exchnage server, I use a POP3 connector to transfer mails from my 1st ISP (let's name it FIRSTISP.COM) and a SMTP connector with a 2nd ISP (SECISP.COM). Our mail are designed as firstname.name@FIRSTISP.COM Most of my users are on the LAN and send/receive mails without problem except when sending to a user (designed as a Contact in AD) which have a mail address as others (firstname.name@FIRSTISP.COM) but not on the LAN, he's on a remote site with a DSL line. When sending to him a mail, I receive a message from system admin which said my mail cannot be sent as it seems to be sent continuously between 2 servers. Logs show the categorizer has detected a forward loop.... What do I need to check to avoid it and send mails with no problem to him ? Cheers, Olivier

It sounds like the issue is that your Exchange server thinks it hosts this domain, and when you try to send mail to this user it can't deliver it because there isn't actually a mailbox. While I haven't used your exact configuration before (seems like you should colapse your mailflow a bit), there is an option on the Messages tab of the SMTP virtual server called "Forward all mail with unresolved recipients to host:". try putting the ip of your ISP's MX server here. and you'll need to remove the contact from AD, or create the user a real mailbox, which might be another, better option. This problem would likley occur for any contact that points back to the internal domain, regardless of connectors. BTW, what is the smtp domain name on your recipient policy?

It is @firstisp.com. Maybe it's not the good way ? I've seen on a forum that we should use for example @domain.local as policy but how our customers will have our address as @firstisp.com ?

it just messes up smtp routing when you're named the same as your isp when you aren't actually hosting your mail. the best way around it is to forward like i said above, but don't have any contact loops.

Done ... and it works ! Many thanks ...

Glad I could help. Please mark the post as answered.