Not for everyone:
using your own postfix-smtp-server works perfect, if you can set it up correctly.
You'll have to create an SPF-record in the DNS-setting for your (from)domain and you need access to the internet from your postfix-smtp-server on port 25. AND you have to make sure the security of postfix is up to par! You don't want a spammer to get access and misuse/abuse you gateway 