أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
Microsoft Exchange Server has internal SMTP relay. That's why any internal user can spamming easily through SMTP tools (e.g. Telnet, etc).
follow this linkhttps://www.codetwo.com/admins-blog/how-to-prevent-internal-email-spoofing-in-exchange/