Sending from multiple email addresses using POP


I have an app with many users who need to send and receive emails. My
client does not want to have a local smtp server (if he can avoid it
:). I can receive emails on a per user basis using Net::pop. What has
me stumped is how to send email from different email accounts(but same

When I try to send if the FROM: does not match the smtp login account
the mail server does not send it. Since Rails has only one app wide
smtp configuration is there a way to use a per user login/auth to send
email as well?



PS: Our app will be deployed on a separate VPS for each of my client's
customers and each customer is a multiuser env.