You can send an email from any account configured on your phone. If you have multiple email accounts, you'll see a From field on the Vlingo email landing screen. To change the account from which this particular email will be sent, click the From field and select one of your other accounts.
Vlingo sends emails from your default email account. To change the default email address, go to the Vlingo Home page and click Options. On the Options page under Applications, change the Default Email address option.