Sometimes the GUI seem not to work for some very basic task such as retreiving addresses from the address book while typing or sending an email.

When this happens I check the browser JS console and I find plenty of blocked CORS request to a server which is not mine:

Bloccata richiesta multiorigine (cross-origin): il criterio di corrispondenza dell’origine non consente la lettura della risorsa remota da https://e-aj.my.com/SOGo/so/myuser@mydomain.it/Mail/0/folderDrafts/newDraft1582625188-1/save. Motivo: richiesta CORS non riuscita

The problem is: https://e-aj.my.com is not my server. I don't know who these people are, I never typed this address anywhere in my configurations.
It looks as if this URL is hardcoded somewhere.

Strangely enough, this doesn't happen always but only when working on some messages.

I tried various browsers (Firefox, Chrome, Edge, Safari) on various platforms (Windows 10, Windows 7, Mac OS, Ubuntu) and the issue happens with all the configurations, always with the same messages.
So if a message has issues, it will have issues with any browser or system.

This happens only when replying or forwarding an existing message.
Till now it never happened with a new message.