Yes, postfix is perfectly capable of this.
Take a look at the Postfix HOWTO:
(those two pages are linked from the fairly extensive official Postfix docs page
For an example server, the configuration in master.cf looks like:
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (yes) (never) (100)
smtp inet n - n - - smtpd
submission inet n - n - - smtpd
smtps inet n - n - - smtpd
And main.cf has a line like:
In this case, authentication is only turned on for the submission (587) and SMTPS (465) ports.
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