Not really. Postfix is very robust against attackers and knows to how to deal with bots by default. It makes sense to also configure SPF, DKIM and DMARC for your own safety.

If you want to stop the attackers from hammering, you can also add fail2ban.

If you want to avoid spam, you can attach a spamfilter to the delivery agent and let Sieve do the rest.

I’ve been running my postfix/dovecot combo using 4 mail domains for over 5 years without any problems. It’s simply fantastic.