I updated the website to Moodle 3.7.2 ten days ago, and up until today, the error was nowhere to be seen.
However, I just noticed that a message I sent two day ago got repeated yesterday at 22:30...
My website is hosted at one.com and I am using their standard provided SMTP server details... Could you explain how the SMTP server (which deals with emails) could be related to this problem?
And should I try switching SMTP Server in Site administration > Server > Email > Outgoing mail configuration to eg. an external SMTP provider?
And should I try switching SMTP Server in Site administration > Server > Email > Outgoing mail configuration to eg. an external SMTP provider?