Could not instantiate mail function - works for one account, fails for another

I have two different domains on the same server running PHPList 3.3.3.

One account can send emails without any issues. The other account gets the failure: Could not instantiate mail function.

I’m just trying to send one test mail, to my own account, which is not blocked and is not on the same server.

The sender and domain are the same in each account - two different domains, but in each configuration only one domain is involved.

I control the DNS for both configurations - configured off site - and they are identical.

I control the server, and though I’m able to perform basic tasks I’m not a full fledged admin.

I control all of the configuration information for both accounts and can find no differences.

I’ve never been able to use SMTP delivery in either account, but both have been working for years with earlier versions - only recently failing in an upgrade.

For SMTP on the working account, if I change the settings in the config.php file I get this error: Error sending email to SMTP connect() failed

Where should I be looking to get the “broken” account to work? I’ve checked the DNS configuration, the website configuration (DirectAdmin in both cases), the account definitions and file privileges and of course the PHPList config.php files, and I can see no differences.

There are no error logs that tell me anything of interest when I get an instantiate failure. Nothing in the server MAIL logs. Nothing in the Apache logs.

I’m at a loss where to look next, and I’m not trying to get the SMTP function to work, only the standard PHPMailer function.


Just for closure, I switched this account to SMTP with help… and though I did not solve this problem I’m running again.