Depends who you are trying to send email to. There are email providers that use IP blacklist maintainers that require you to pay a fee to keep off their blackli

Depends who you are trying to send email to. There are email providers that use IP blacklist maintainers that require you to pay a fee to keep off their blacklist if you are not a big provider (eg. they blacklist all VPS hosting companies). This was the final straw that had me switch to using a provider for SMTP (not MX, I run it still).