Advice on debugging "Sent test mail to: ... failed"

I’ve just installed phpList v3.5.2 on my namesco web server which has php 7.2.

Ultimately I want to set this up with Amazon SES but I’m not a web developer so I’m trying to get there in steps. I am testing the email sending with a test campaign and using the “Send Test” button at the bottom to send to a single gmail account.

  • So far this has been successful with the default config.php settings that use php mail()
  • I have also changed the config settings to use my namesco SMTP server and that also successfully sent a mail
  • I have changed the config settings to use SMTP settings for a new SendGrid account (testing with this because its free) and it is failing to send.

I don’t imagine anyone can help me fix the problem directly, but I don’t know how to get more information on the failure. Maybe I have made a mistake in the config file (I don’t think so), maybe I have misunderstood how to use the SendGrid SMTP settings, or maybe I need to configure something else in my namesco web server. I just don’t know how to find out - is there any way to get more information on the “failed” email?


Update: I just tried with a SendInBlue account and that worked fine, so it looks like I was just having a problem with SendGrid. I’d still like to know how you might go about debugging this though, as I still don’t know what was wrong.

@MrEmails2 There is a setting to enable debug output when sending using smtp.
Look in config_extended.php then copy the setting into your config.php file

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Fantastic, I should have paid more attention to the extra config list (though the link given on that debug line is broken).

It worked and pointed me in the right direction. Turns out it was a 550 error because the sender could not be verified. Fixed that now and it sent successfully. Funny how the SendInBlue service I tried did not require such verification.