Some Linux systems ship with multiple Berkeley DB implementations.
Normally, Postfix builds with the default DB version that ships
with the system.
Warning: some Linux system libraries use Berkeley DB. If you
compile Postfix with a non-default Berkeley DB implementation, then
every Postfix program will dump core because either the system
library or Postfix itself ends up using the wrong version.
On Linux, you need to edit the makedefs script in order to
specify a non-default DB library. The reason is that the location
of the default db.h include file changes randomly between vendors
and between versions, so that Postfix has to choose the file for
Warning: the file format produced by Berkeley DB version 1 is
not compatible with that of versions 2 and 3 (versions 2 and 3 have
the same format). If you switch between DB versions, then you may
have to rebuild all your Postfix DB files.
Warning: if you use Berkeley DB version 2 or later, do not
enable DB 1.85 compatibility mode. Doing so would break fcntl file
Warning: if you use Perl to manipulate Postfix's Berkeley DB
files, then you need to use the same Berkeley DB version in Perl
as in Postfix.