cd /usr/ports/databases/db3
make deinstall
rehash
cd ../p5-BerkeleyDB
make deinstall
rehash
cd /etc

ee /etc/make.conf

add:
WITH_BDB_VER=43

cd /usr/ports/databases/db43
make install
rehash

cd /usr/ports/databases/p5-BerkeleyDB
make install
rehash

cd /usr/ports/mail/postfix
make install
rehash

cd /usr/ports/mail/p5-Mail-SpamAssassin
make install
rehash

cd /usr/ports/security/amavisd-new
make install
rehash

cd /usr/ports/security/clamav
make install
rehash