Thank you Big Booger!
Are you sending out mass mailings? Perhaps your account(s) have been blacklisted by the SMTP server?
My biggest "mass emailings" are only about 230 recipients! And even when I split this amount, I still got the same error msg! But whether my account was blacklisted by the SMTP server...I don't know. How can I find out? Is MY server the server of SMTP too?
Are you using any mail filters?
Not that I know, except for the standard ones that all servers use...and which I never understood.
Have you tried disabling the antivirus software?
I tried disabling my Norton Anti Virus, but I can't find WHERE the "disable" button is. Could you direct me please?
Have you given Thunderbird or Eudora a chance?
I'm going to try Thunderbird or Eudora though I hadn't so far because I thought they are WEB emails (which I detest)...are they? I opened a gmail so if it doesn't work with OE I'll use that one...which I don't like not only because it's a WEB email and has too busy an interface but also because it didn't accept my list of recipients either!!! No error msg explaning.

Thank you again! Adela