My contact form on Joomla is not sending mails to my Google-hosted domain. Instead I get a failure notice in my webmail saying:
Why is contact form trying to send to email@example.com? Joomla users with Google Apps: is your contact form working?Remote host said: 550 <firstname.lastname@example.org>: No thank you rejected: Account Unavailable: Possible Forgery
I also installed Zen Cart, and its contact form is working (emails reach my admin account on Google).
PS. My Joomla mail settings are attached.