Some cable companies will not allow you to SEND email from your website's mail server so the recipient receives your message showing that it is from firstname.lastname@example.org
You can work around this by making the following changes in the settings in the email program on your computer.
Open your Outlook or Outlook Express email program, and click on TOOLS and click ACCOUNTS.
Select your default email account and click the PROPERTIES button.
Click on the SERVERS tab and change the name of your OUTGOING SMTP
mail server to the name of your cable internet provider's mail server and click the SETTINGS button. Leave the incoming Mail Server ACCOUNT NAME associated with your website domain name.
Click the LOG ON USING radio button and enter the name and password with the email address associated with your Cable provider (not your website email address).
Once the settings shown above have been configured, email sent from this account will arrive in the recipient's inbox, coming from your email address at your website domain.