I've got WordPress 2.2.2 running on a Windows server. I'm using the Dagon Design Form Mailer 5.3.3 script. The webserver is using qmail for the SMTP server.
When I fill out the contact form, I get duplicate copies of the email message. That's right 2 emails each time the form is submitted.
I've verified that this is not a qmail SMTP issue by writing a simple mail() PHP script and running it on the same site, and it only sends me 1 e-mail.