error: Error writing mail data to file

Hi @creativitijd,

Thanks for your feedback and sorry to hear that.
When you used the “test email” feature, did you try with the “Don’t wait for cron job” checkbox checked or not?

To give more informations, if it is checked, the mail will directly be sent to SMTP server without going through the disk queue. This help to determine if the problem come from SMTP configuration or server file system issue.

Yours faithfully.
Birmania