> I am sure these test will be successful as the initial test trying to > establish a STARTTLS session already was successful. So your problem is > client based. Check for firewalling and anti-virus scanners (outbound > mail scanning), as I told you before. The issue (especially Norton's > thing) is well known and an ongoing pain. You will find many hits and > references to this through google. I.e. > > http://www.cs.wisc.edu/csl/old-doc/info/smtp-auth/ > > Alexander > Below is quoted from the above web site: "NOTE: If your Internet Service Provider blocks SMTP traffic using Port 25, you must configure your email client to use Port 587 instead. Some ISPs block Port 25 in an attempt to reduce spam and viruses. The CSL has made Port 587 (a reserved port for email message submission) available for authenticated SMTP. Please see configuration information for your specific email client below..." The Symantec Antivirus checks port 25 for outgoing emails. So, if we could set port 587 for smtp on the server side, then it may work with symentac antivirus. Is it true? If yes, how to set the port 587 on the server side for smtp? Will that work anyway? Thanks! Hongwei