MFA

the mfa.nsf is a solution that enable MFA (multi factor authentication) for Domino.

Setup

copy mfa.nsf database to Domino data folder (it goes with predefined setup of documents, don't remove them, they are part of a solution).
sign mfa.nsf with your server id
create Config document in mfa.nsf
you need to properly configure iMessageURL field (it's a service that sends SMS), see details https://github.com/Domino-iMessageSMS/iMessageSMS
in the view Template press button 'Update Login Form' (that should generate Login form inside of MFA.nsf, which is mandatory by domcfg.nsf).
replicate mfa.nsf to other Domino servers if needed (also configure connection/replication documents), so data are synchronized as fast as possible.