I've been using EPiServer's built-in subscription functionality on a few 4.61 projects with no problems... when i tried it on my first version 5 one i had a few issues - namely the subject and read more links were in Swedish and i couldn't set the mail from address... Here's how i fixed them:

1. Swedish Text - Default language was set to Swedish (based on the demo content added at install time i think) - thanks EPiServer support for helping me with this.
2. "From" Email Address (and the "Read More", email "body text" etc) In 4.61 these were set on the Subscription page type, in version 5 this is done on the page that is marked for subscription (has EPSUBSCRIBE property) - you add the following properties (should be fairly obvious what they're for):
   • MailFrom
   • MailSubject
   • MailBody
   • MailReadMore

The change in point two is great - as now you can set different email address/email bodies per subscription area!