Hello, I thought "Outlook Express" forum closer? But there was no "Start New Thread" button, so...

(winXP Pro; OE 6.0; IE 6.0; Dell Dimension XPS T450MHz Pentium III; Norton AV)

Outlook Express is not sending out my msgs and for the last 2 days they have been accumulating in the Outbox. All other OE functions work properly. For the last 2 days I've been on the phone with my server (RCN) and they couldn't help. They sent a technician, he tried to fix it and couldn't . He then called RCN himself and they couldn't help. These are the errors I receive each time I try to send my messages:

Error on one account:

The message could not be sent because the server rejected the sender's e-mail address. The sender's e-mail address was '[email protected]'. Subject 'Perplexed at your communication!', Account: 'pop.rcn.com', Server: 'smtp.rcn.com', Protocol: SMTP, Server Response: '530 Authentication required', Port: 25, Secure(SSL): No, Server Error: 530, Error Number: 0x800CCC78

Error on the other account:

The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was '[email protected]'. Subject 'Fw: BRAVO JILL ROBINSON for GREAT SYMPOSIUM to HELP CHINESE CATS/DOGS!!!!!!!!!', Account: 'pop.rcn.com', Server: 'smtp.rcn.com', Protocol: SMTP, Server Response: '452 #4.5.3 Too many recipients.', Port: 25, Secure(SSL): No, Server Error: 452, Error Number: 0x800CCC79
The "one of the recipients was rejected", it says it in each and all the messages. (They should revise their error msgs!)

As to "too many recipients" (452), I was told on the phone I can send up to 400 per message per hour... but my list consists of only 230 recipients!!!

What I did: I moved those messages from the outbox to a temporary folder, leaving only one in the outbox ...It didn't get sent out! I split the list in two and sent it out twice...still didn't get sent out!

I'm at the end of the rope...hope someone knows what to do? So sorry for lengthy message, and thanks so very much for any help! Adela