I can receive, but not send e-mail messages

You can check several things to help resolve being able to receive but not send e-mail messages.

Outgoing SMTP server requires authentication.

If your outgoing SMTP server requires authentication, verify that you have you configured Outlook to use SMTP authentication.

Your Internet Service Provider (ISP) can tell you if you need to turn on SMTP authentication. If your ISP instructs you to turn on this feature, you can verify by using the Internet E-mail Settings dialog box.

Note Only POP3 and IMAP e-mail accounts allow SMTP authentication to be turned on.

How ?

1. On the Tools menu, click E-mail Accounts.
2. Select View or change existing e-mail accounts, and then click Next.
3. Select the name of the e-mail account, and then click Change.
4. Click More Settings.
5. On the Outgoing Server tab, verify that the My outgoing server (SMTP) requires authentication check box is selected.

Outgoing SMTP server requires Secure Password Authentication (SPA)

If SPA is required by your Internet Service Provider, verify that you have configured Outlook to use SPA

Your ISP can tell you if SPA is required with your account. If your ISP instructs you to turn on this feature, you can verify by using the Internet E-mail Settings dialog box.

Note Only POP3, IMAP, and HTTP e-mail accounts allow SPA to be turned on.

How ?

1. On the Tools menu, click E-mail Accounts.
2. Select View or change existing e-mail accounts, and then click Next.
3. Select the name of the e-mail account, and then click Change.
4. Under Logon Information, verify that the Log on using Secure Password Authentication (SPA) check box is selected.