Mail is not being sent in ad poster sidebar contact form email
Since I ordered Classi Press, I have issues when users try to contact owner ads (ad poster sidebar contact form email). In this occasion, I installed plugin WP
-MAIL-SMTP and things started working fine. But, when I upgraded to Wordpress multisite (WPMU), this plugin stopped working properly and the issue took place again.
The only one feature that is not working as expected is "ad poster sidebar contact form email"! All other features that send emails are working fine!
I thought it was related to php mail function being deactivated by my host provider, but it's not.
To prove that, they installed a demo script to show me that it's not deactivated.
Considering this, what can be done to fix the classipress mail function?