שגיאת SMTP 503 5.5.1: אימות לא הופעל

makes sense, I don’t use SASL so I set those options to make it more secure.
What methods are available?
Also why is SASL mandatory? I had it disabled before and SMTP worked in all other applications like nextcloud and thunderbird

SASL is only needed to send email to remote servers, but this server only works locally

Thanks