I would recommend mail-receiver for reply-by-email, as this is a feature i use more often, so my lecturer’s emails land in the correct event topic with the lecture slides..
For email-in , i think POP3 corresponds to per-category Settings, though i’ve never tried POP3:
I did once pay for private email but cancelled it after the first month, in favour of pointing the MX record at the VPS (Custom MX).