[3.0]: Unable to send test email with MailAgent

[Oldiesmann]

Basic Information

Attempting to send a test email from the admin center results in an error.

Steps to reproduce

1. Go to Admin -> Maintenance -> Mail -> Send Test
2. Attempt to send a test email

Expected result

Test email sends successfully

Actual result

Blank screen / error

Version/Git revision

4e54200

Database Engine

All

Database Version

No response

PHP Version

8.4.3

Logs

Additional Information

I don't know if this applies to everything that sends mail or just the test email. I tried sending a newsletter from two test boards (one local, one on my server) and neither one arrived, but no errors are logged related to it and the mail queue is empty afterwards.

[Sesquipedalian]

@jdarwood007, can I assign this to you?