Upgrading Sendmail's DB

[antenneX]

Running FBSD-4.10p2/Sendmail-8.12.11

I want to upgrade the Sendmail's Berkley DB to 4.2x, but since Sendmail
is part of my base OS, what is best way to recompile Sendmail with the
new DB?

BTW, I use sources if not evident.

Do I need to recompile the whole OS which includes Sendmail or is there
an easier way to just update the Sendmail?

The Sendmail site is not very clear on this. It does say if the new DB
4.2x is installed and the new libraries  are there, it will find it and
use it instead of the old DB2 & that NEWDB takes care of it if it can
find the library named libdba.a or libdb.so.

Advice needed and appreciated.....

Best regards,

Jack L. Stone