Joffm, Thank you for the reply! But when I installed XAMPP on mac, I don't find mercury mail inside, only with Apache, MySQL and ProFTPD. How do I add mercury to XAMPP?

I always would use an existing SMTP server over installing and configuring my own email server.

I would never use PHP (just too many problems and most probably your emails will end up in Spam anyway), always go with a good SMTP server. But keep in mind, not every SMTP account allows sending mass emails like invitations. You can quickly run into blocks by your email provider if your smtp account has certain limits.

This is what apachefriends say about email on Mac.
www.apachefriends.org/faq_osx.html
"How do I send email with XAMPP?"


And you may try this:
www.geeksforgeeks.org/how-to-configure-x...localhost-using-php/

Joffm