Hi,This is a weird issue I've never seen before. We have created an email address on our Exchange server called jobapplications@xxxx.xx.xx however, we can't get the address to receive external mail (from hotmail, gmail, etc). The mailbox works internally, but nothing from external senders. We've tried deleting the mailbox, user account, everything related to this address, but the same thing happens when we recreate the account. So we thought try jobapplications2@ and that worked fine. Anything I could look at to help me work out why one works and the other doesn't?! Cheers!

Hi,You can check from a third party email validation site to check whether you could successfully relay to the concerned email address.http://hexillion.com/email_validation/Check your antispam provider, (locally hosted or hosted solution) whether this specific email id is blocked.Hope this helps.Regards,Tariq

Thanks for the Hexillion address, it really helped. The RCPT address is coming up as 550 5.1.1 User unknown. I'll be able to do more check here now.I have since discovered that another department have installed an Exchange 2003 server for an older development tool they use. So, I'm guessing that the 2003 server is trying to relay the messages, however the routing between 2007 and 2003 isn't right. Going to have a look now, but if anyone else has other suggestions, I'd really appreciate it.

Possible cause (Exchange 2007): If the inbound message contains a recipient that is on the Recipient Block list, the Edge Transport server sends a "550 5.1.1 User unknown" SMTP session error to the sending server. If the inbound message contains a recipient that does not match any recipients in Recipient Lookup, the Edge Transport server sends a "550 5.1.1 User unknown" SMTP session error to the sending server. --------Refer to <Recipient Filtering> Possible cause (Exchange 2003): Exchange Server determines whether the Filter recipients who are not in the Directory check box is selected on the Recipient Filtering tab of the Message Delivery Properties dialog box. If this check box is selected, and if the recipient does not appear in the Active Directory directory service, Exchange Server returns 550 5.1.1 User unknown. --------Refer to <KB 823866> Check info: 1. Please describe the exchange topology 2. Is jobapplicationsa regular user mailbox? 3. You said that jobapplicationsa cant receive mail from hotmail and gmail, is there any external domain that is able to send mail to jobapplicationsa? 4. Since external domains cant send mails to jobapplicationsa, is there any NDR on their side? 5. Could jobapplicationsa send mail to external domains? Troubleshooting: 1. Please disable all 3rd party software on the exchange environment, and then test mail flow again 2. Monitor the message tracking log on the SMTP gateway exchange server, see if theres any related info

Has the issue been solved? Any update?