FormIt connection to mail server fail on Revo 2.3.1

I've got a problem which seems to be unique, but repeatable. I've been using FormIt on multiple sites for ages without issue, but in the past couple of days I've come against a problem where FormIt (and QuickEmail, for that matter) can't connect to php mail on my server. I can confirm that it's entirely a result of the upgrade to 2.3.1 - I tested a basic form that was running on a 2.2.14 installation that worked, performed the upgrade, then tested the form again without success.

This is all based on default mail settings that I've not ever had to change. FormIt outputs an error message in the browser saying "Connection with the server could not be established." Also, in Developers Tools there's a 404 error for a call to www.domainname.com/php/mail.php. QuickEmail has the following output:

Send Failed
Mailer error info: Could not instantiate mail function.
Server Debug Information: (blank)

Any ideas?

Bump.

Just confirming, this issue is less related to FormIt, and more related to the MODx mail functions. Does anyone have any thoughts as to what could be causing this?

Can you tell us more about the hosting environment?

It may be that the mail server at your host is flaky, or the hosting service has changed a mail policy that's effecting you.

Switching to SMTP by changing the MODX SMTP System Settings would probably solve it.