Yes, blocking port 25 outbound is incredibly common by default. Even on some server connections. It is probably better overall for exactly the reasons that you mentioned.
Or just don’t self-host email
IMHO this is a bit overblown. Hosting inbound is fairly easy. Mail senders (probably for the worst) are very forgiving even if your TLS cert is expired you will probably get mail. Plus senders are supposed to retry for days if you have downtime.
However it is unfortunately true that due to spam sending is a huge pain because IPv4 reputation is a huge component. Sure you can get GMail to trust your domain after a month or so of sending if you have decent volume. But other providers who you may mail once a year are just going to go off of IP reputation. However email was basically designed for forwarding and you can use a service like AWS SES to forward your email from a trusted IP pretty easily. If you are low volume (like personal mail) there are tons of services that will do this for free.
quokka1@mastodon.au 2 days ago
@SheeEttin @AdrianTheFrog +1 Email for me is basically irrelevant. MFA resets, adverts from companies I forgot to unsubscribe from and a couple of bills. No personal correspondence or anything I would think is worth self-hosting it for these days. Other than many headaches.