Does anyone have an idea of software or scripts that manage email marketing that may allow users to unsubscribe? I need something that produces multiple email client compatible code.

Thanks in Advance.

Are you talking auto responder?

I would suggest a service like MailChimp They are very reasonably priced, and provide everything you need to successfully send email in bulk.

I would suggest Omnistar Mailer http://www.omnistarmailer.com

Not quite sure I understand the question but I would suggest the biggest 2:

Aweber and iContact.

Originally Posted by ATLChris

I would suggest a service like MailChimp They are very reasonably priced, and provide everything you need to successfully send email in bulk.

I strongly agree with this suggestion...Not only are the first 500 subscribers FREE, but the backend trumps Aweber (I hate when clients insist on Aweber, thir site is such a mess).

You might also try Campaign Monitor, last time I looked they were cheaper than MailChimp.