I am using Contact Form 7 with Wordpress, but I am experiencing an email compatibility issue.
I have the form setup to email to email@domain.ca, domain.ca being the domain of the website hosting the site. The email address exists and works great, however the Contact Form keeps failing on send.
If I change the email address to any of my Gmail or other accounts, it works fine.
I am looking for ideas or suggestions as to how I might debug this. Is it because the site is hosted on a shared hosting server but the mail server is in-house at the physical location?
Any ideas would be great.
Ended up being an MX Entry problem with the shared host. I had to set the MX Entry to send mail to an external host instead of the internal mail servers (it didn't realize the mail server was external).
Problem solved and all is well.
EDIT: We have run into this issue multiple times now with the hosting. Essentially, cPanel gives you an option to say that mail servers are external, but it often fails to deliver on actually making the change. We have to remove the mail servers and hardcode the external one in order to make it work properly and consistently.
Might be php or smtp mail restrictions at your hosting service. Try http://wordpress.org/extend/plugins/wp-mail-smtp/
来源：https://stackoverflow.com/questions/3472848/wordpress-contact-form-7-not-sending-to-certain-email