Many ISP's block the sending of email via your domain name through port 25.

Try changing your outgoing SMTP port from 25 to our work around port 26. See how-to's below:

Microsoft Outlook 2002/2003:

1. From the "Tools" menu, select "E-mail Accounts"
2. Select "View or Change existing email accounts" and click on "Next"
3. Select your POP account and click on the "Change" button
4. Next, click on "More Settings"
5. Click on the "Advanced" tab
6. Next to "Outgoing server (SMTP), change port 25 to 26
7. Click "OK", then click "Next" and "Finish"

Microsoft Outlook 98/2000, Outlook Express:

1. From the "Tools" menu, select "Accounts"
2. Select your POP account and click on the "Properties" button
3. Click on the "Advanced" tab
4. Next to "Outgoing server (SMTP), change port 25 to 26
5. Click "Apply", then click "OK" and "Close"

Netscape 7:

1. From the "Windows" menu select "Mail & Newsgroups"
2. From the "Edit" menu select "Mail & Newsgroups Account Settings"
3. Scroll down and click on "Outgoing Server (SMTP)" on the left hand side
4. On the window to your right, enter 26 next to "Port"
5. Click "OK"

Eudora:
See: http://www.eudora.com/techsupport/kb/1501hq.html

IncrediMail:

1. From the "Tools" menu, select "Accounts"
2. Select your POP account and click on the "Properties" button
3. Click on the "Advanced" tab
4. Next to "Outgoing server (SMTP), change port 25 to 26
5. Click "Apply", then click "OK" and "Close"