How to make the "From" field of my emails to be myemail@mydomain.com instead of catchall@mydomain.com?

This is a configuration that should be done in your email client.

If you use "Outlook Express" follow these steps:

1. Select Tools from the top navigation bar. Then Accounts.
2. Select the appropriate mail account ("catchall@mydomain.com").
3. Click on the Properties button.
4. Fill the field Email address with myemail@mydomain.com.
5. Click on the OK button and then on the "Close" button.

If you use "Microsoft Outlook 2002/XP" follow these steps:

1. Select Tools from the top navigation bar. Then Email Accounts.
2. Select the appropriate mail account ("catchall@mydomain.com").
3. Click on the Change button.
4. Fill the field Email address with myemail@mydomain.com.
5. Click Next and finally the Finish button to save your changes.