Outlook Express Error 0x800CCC78

Chasti,

Open OE and go to Tools|Accounts. Highlight your account and select Properties. On the Servers tab make sure that all the entries there are the ones specified by your ISP. Either your SMTP server is not identified correctly or you have told OE that it requires the server requires authentication and it doesn't (or vice versa).

Chasti,
Whenever I get weird things like this, I will reboot the computer which sometimes fixes a problem. Try that first. If you still have a problem, check that your mail account is set up properly...

Click on Tools, then Accounts
Select your mail account, click the property button
Make sure everything appears correct in this "General" screen, especially your email
Click on "Servers" tab, make sure everything here is what it's supposed to be, especially the SMTP outgoing mail. Every server is different, so it's hard to tell you what it should be exactly. Otherwise, you can go to your server's website and find the documentation there for setting up email accounts and also they might have a troubleshooting section. I hope this helps!

Oh....also, I did a little research and found the following at the Microsoft Knowledge base. It didn't really say how to resolve your issue though, but thought I pass it along.

website address: http://support.microsoft.com/default.aspx?scid=kb;en-us;208814

0x800CCC78 SMTP_REJECTED_SENDER
Unknown sender. This is caused by
having the incorrect e-mail address
the Reply-To field.

That error message is mentioned under the SMTP errors at this Knowledge Base link as Denny Said.

http://support.microsoft.com/default.aspx?scid=kb;en-us;208814

I truly appreciate all the input on this problem.  I checked all the settings in mail properties and even called my ISP to make sure all was correct.  But I'm still getting the same.  I was told by my ISP that OE is being treated as a free email such as Hotmail, and it was a software problem, not ISP problem.  Does this make sense to anyone?

I also tried toggling the "authentication".....Doesnt work either way.

I didn't realize I could actually look up the error number though, thanks!  That was good to know.

Anymore trouble shooting would be greatly appreciated.

Thanks again.

Hi,
Just a thought, disable Email scanning by your antivirus as this step is useless anyways.
Now delete and recreate the email account settings.

and then try and send the mail.

==rohini

The error message indicates a problem in the General tab in the account properties.  The email address of the sender must be a valid email address in the form of *johndoe@yourisp.net*, whatever you use as your email address.  Without both parts joined by the @ sign, the email will be rejected with the message you received.