PHP contact form giving 550 5.1.1, “User unknown”

July 14, 2014 1.5k views

Hi, I run an Ubuntu server with Apache2. I have a PHP contact form in domain1.com. The contact form is configured to send messages using SendMail to info@domain2.com (domain2.com is a Zoho hosted email).

A few hours ago I was being able to send messages via contact form, but it suddenly stopped to work and started returning this error:

info@domain2.com... User unknown

Any idea?

1 Answer

Does sending an email to info@domain2.com from your personal email address (Gmail, Hotmail, etc.) work?

Have another answer? Share your knowledge.