I battled this for a good year. The problem was excessive number of mail queues (due to a lot of spam).
On any given day, my exchange front-end server, which communicates in/out for all SMTP traffic to external hosts would have 500-700 queues trying to delivery bad mail. This was because the spam softare I had worked at the mailbox level and not the gateway level. The problem occurred only sometimes, and if a user got the error, they could resend the mail 3 seconds later and it would go right through. I was talking to MS about other issues and asked about the relaying problem. They said that the number of excessive queues would likely cause this problem. No real explanataion as to why aside from the server getting "confused" in SMTP communications, or something of that nature. I installed a Barracuda Spam Firewall at the gateway and it dropped my average SMTP queue counts to 50-75 and the 5.7.1 relay errors dissappeared, so MS was right. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tony Nguyen Sent: Thursday, October 19, 2006 6:09 PM To: Exchange Discussions Subject: Still looking I have on this for a week now and still looking for answer. Could someone point me in the right direction please. We receive email and it all come in just fine but when we do reply or even a new email we get a smtp;550 5.7.1 Unable to relay or smtp;554 <[EMAIL PROTECTED]>: Relay access denied or smtp;550 5.1.1 <[EMAIL PROTECTED]>... User unknown and sometime the reply go through email just fine and sometime it does not. I have checked the all the IIS and SMTP but everything look fine and email is still flowing with some other domain just fine. Anyone have a check list that I can use to trouble shoot this? Thank Tony [Disclaimer] The receiving party represents and warrants that no technical data furnished by the disclosing party shall be exported from the United States without first complying with all requirements of the International Traffic in Arms Regulations and the Export Administration Act and regulations hereunder, including the requirement for obtaining any export license, if applicable. The receiving party shall first obtain the written consent of the disclosing party prior to submitting any request for authority to export any such technical data. The receiving party shall indemnify and hold the disclosing party harmless of all claims, demands, damages, costs, fines, penalties, attorney's fees and all other expenses arising from failure of the Receiving party to comply with this clause or the International Traffic in Arms Regulations and the Export Administration Act and applicable regulations. The receiving party may make the technical data furnished available only to its employees, contract employees and other parties working on the program within the receiving party's facility and having a "need to know" with respect to said purpose. In connection therewith, the parties shall advise each such employee, contract employee or other party of its obligations under this agreement. _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Web Interface: http://intm-dl.sparklist.com/read/?forum=exchange To subscribe: http://e-newsletters.internet.com/discussionlists.html/ To unsubscribe send a blank email to [EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] To unsubscribe via postal mail, please contact us at: Jupitermedia Corp. Attn: Discussion List Management 475 Park Avenue South New York, NY 10016 Please include the email address which you have been contacted with. _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Web Interface: http://intm-dl.sparklist.com/read/?forum=exchange To subscribe: http://e-newsletters.internet.com/discussionlists.html/ To unsubscribe send a blank email to [EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] To unsubscribe via postal mail, please contact us at: Jupitermedia Corp. Attn: Discussion List Management 475 Park Avenue South New York, NY 10016 Please include the email address which you have been contacted with.
