Yes. If you'd like to send an email from a different account, say, user@yahoo.com, with Outlook Express, you will just need to configure the software properly. Follow the steps below:

1. Open Outlook Express.
2. From the Tools menu, select Accounts.
3. Click on the Add button and select Mail.
4. In the Display name text box, type your name.
5. Click Next.
6. Check the circle next to I already have an email
   address that I'd like to use.
7. In the Email address text box, type your email address (for example, user@yahoo.com).
8. Click Next.
9. From the My incoming mail server is drop-down menu, select POP3.
10. In the Incoming mail server box, type the correct POP server (in this example it would be pop.mail.yahoo.com)
11. In the Outgoing mail server box, type the correct SMTP server (in this example it would be smtp.mail.yahoo.com)
12. Click Next.
13. In the Account name box, type your email account ID.
14. In the Password box, type your password.
15. Note: your password may be case-sensitive.
16. If you want to have your password saved, so that you don't have to type it when checking email, place a check in the Remember password box.
17. Click Next.
18. Click on the Finish button to save your settings.