Peculiar problem this week with a client simply moving hosting account and not being able to receive contact form emails using Custom Contact Forms in WordPress .
The forms was actually processing perfectly, it was actually storing each enquiry into the “Saved Form Submissions” area however, no emails were being sent.
Turns out this was an issue with and external MX server and cPanel wasn’t configured correctly.
Fix:
Log into cPanel > open MX Entry (under Mail options) and enter your MX destination.
Problem resolved itself instantly after this change.