Using other blacklists for host blocking?

[Garry]

Seeing the rising amount of failed SSH attempts to several of the boxes
I have, I was wondering ... has anyone here tried to use some other
blacklists to block incoming MTA access?

Assuming that a large amount of spam is delivered through botnets, which
may also be used for other types of attacks, using data from one attack
vector might be helpful in taking care of other things, too ...
especially as things like failed SSH connections are more objective than
deciding whether a mail is spam or not ...

Any comments?

-garry