Installing SpamAssassin on Mac OS X 10.13 High Sierra
Mac OS X 10.13 (High Sierra) comes with Berkeley DB 1.x which prevents the CPAN module DB_File from installing.
The symptom when you try to install SpamAssassin is that during make test
t/bayesdbm.t will take a very long time and fill the disk, showing error lines "HASH: Out of overflow pages. Increase page size".
A solution is to install homebrew and install a newer Berkeley DB with the command
brew install berkeley-db
After doing that DB_File can be installed from CPAN.
The system Perl will not use the new install of Berkeley DB, continuing to use the one baked into libSystem.B.dylib. It will be necessary to install Perl yourself, such as by using Macports, homebrew, or perlbrew, then installing DB_File from CPAN so that DB_File is built using the new berkeley-db.