Microsoft is discontinuing basic authentication via IMAP and SMTP so that method will most likely be an issue sooner or later any way.
Apart from that - the email address being used for the sendout (aka the from address) is not configured in the SMTP dialogue of the notification channel. This might be a bit confusing, you can find said mail adress in the email channels settings.
Thanks for the answer, is there going to be a implementation of another method to send notifications?
And if so, is there an estimate when it is going to be implementated?