Another is most ISPs will put your IP in the PBL so unless you use a relay your outbound email is going nowhere. Google fiber was slow on updating their PBL when they rolled out service in my area so I got to send direct for several months before having to use an external relay.

I use a free outbound smtp relay that lets me do like 5k emails on the free tier. I use it primarily for alerts and Immich updates / new user links. But I don’t do inbound so don’t have to expose any ports. Only time I did was to do validation with the relay so just a few minutes during setup.

Just get two dish washers. Take the clean dishes out of one to use, then put them in the other when done. When full wash, then repeat.

OpenTTD for transportation management is a favorite of mine.