How can I allow my users to configure their account (created w/ devise) with their smtp server, so they can send & recieve emails in my app?
Are there any ruby gems for this specific problem? Or should I just use ActionMailer from Rails? If ActionMailer are there any tutorials on this topic online?
So sending emails is pretty easy, you can just configure ActionMailer with their credentials, but it's a lot more complex to receive emails in an application. There's a brief mention of that here: http://guides.rubyonrails.org/action_mailer_basics.html#receiving-emails
You can use the mail gem to retrieve emails from a pop server which might be what you want: https://github.com/mikel/mail#getting-emails-from-a-pop-server