I have a client with multiple PC's having this issue intermittently. I have had this problem in the past (years), and as I worked to find a solution, it happened to me again. This is not a new issue, nor is it an issue with the basic "setup" of the email accounts.
Intermittently, can be with a new email, or a reply, withor without an attachement, the mail will go to the outbox and this error will appear:
Task '(name of smtp server) - Sending' reported error (0x8004210B) : 'The operation timed out waiting for a response from the sending (SMTP) server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).'
whatever email is in the outbox is now stuck, and new incoming email will continue to come in. the only solution to the problem is to exit Outlook, Ignore the question Outlook presents telling you you have email in the outbox and would you like to send it before you exit (if you try, it fails) and simply start outlook again. this immediately sends all email in the outbox.
In my, and my clients case, we are both using CA ITM anti-virus and spyware, WITHOUT the email scanner. We are not using any added software firewall. This is Windows XP pro, and the Outlook 2003 is SP3 (I remember this issue going back years with no SP and SP2). the account setup is for a POP3 server, and there is basic SMTP auth and no SSL. Pretty basic stuff.
I have found search responses suggesting corrupted account, bad account config, and problems with server. I have read to use the logging feature to find the problem, and when I do all it suggests is that Outlook does not even try to send the email. I have looked into my email server logs (we are NOT using exchange, its a POP3 server) and there is NO entry of any attempt to connect to my server and SMTP the email. I have even changed the SMTP server name in the account settings to the IP address testing if its perhaps a DNS issue. it appears to me to be a total lack of Outlook even trying to make a connection to the email server, even as it reports the error suggesting it had.
there are a few searches that specifically suggest the SP2 and SP3 upgrades had actually fixed this issue, but it appears its back. This problem has become a larger issue as the client does not realize the email had not gone out and it becomes a time sensitve issue. I have been trying to find a solution for weeks, and it appears to be an Intermittment Outlook problem.
Does anyone know of a solution?