Symphony.

I'm running into an issue with the default mail function, which is not producing deliverable mail. Form my hosting company:

Actually your application seems to be using php mail function which doesn't set correct return-path header value. It sets it to httpd@servername that gets blocked at mail server due large nos. of mail sent. So please use phpmailer class and use mail.domainname as smtp. But you need to use smtp authentication. For smtp authentication, please existing email address as user name and its password."

Anyone else had this issue?

I've had the same issue with the PHP mail function in general, not sure there's anything you can do but use SMTP auth instead.

These things actually depend on the hosting company. One of my favorite hosts (if not the one), the German company Hosteurope, implemented a very restrictive, but simple, logic: Sending E-Mails throuh PHP mail or Sendmail will always require a special "From" address, which must be one of your legitimate E-Mail-Addresses. So they can be rather sure you will not send spam this way.

(There are even more restrictions in place, like restrictions to the number of mails you may send in a fixed period of time.)

The effect: Sending mails via Sendmail or PHP mail is fast and reliable. No need to use SMTP authentication.

Thanks for the info,

I ended up using the phpmailer class as the ISP recommended. It's seems pretty nice, maybe suitable as an extension?

I believe thewolf has written a fairly advanced email sending extension which makes use of phpmailer. Not sure if it's ready to be released publicly though.