IP drop list

I wonder if there is an easy way to provide dovecot a flat text file of ipv4 #'s which should be ignored or dropped?

I have accumulated 45,000+ IPs which routinely try dictionary and 12345678 password attempts. The file is too big to create firewall drops, and I don't want to compile with wrappers *if* dovecot has an easy ability to do this. If dovecot could parse a flat text file of IPs and drop connections it would sure put a dent in these attempts.

Thanks.