libmu-dbm6 1:3.9-3.1 (arm64 binary) in ubuntu groovy

 GNU Mailutils is a rich and powerful protocol-independent mail framework.
 It contains a series of useful mail libraries, clients, and servers.
 .
 This is GNU's Mail abstraction library dbm support component. This library
 allows programs to hook into a single library for many different types of
 mail backends. The following backend stores are currently provided: mbox,
 mh, maildir, dotmail, pop3, imap4.