$ sudo apt-get update
$ sudo apt-get install libsasl2-modules-db 

libsasl2-modules-db is installed in your system.

Make ensure the libsasl2-modules-db package were installed using the commands given below,

$ sudo dpkg-query -l | grep libsasl2-modules-db *

You will get with libsasl2-modules-db package name, version, architecture and description in a table

libsasl2-modules-db package basic information: