sendmail-bin binary package in Ubuntu Bionic arm64

 Sendmail is an alternative Mail Transport Agent (MTA) for Debian.
 It is suitable for handling sophisticated mail configurations,
 although this means that its configuration can also be complex.
 .
 Fortunately, simple thing can be done easily, and complex things
 are possible, even if not easily understood ;) Sendmail is the *ONLY*
 MTA with a Turing complete language to control *ALL* aspects of delivery!
 .
 Sendmail provides Security and SPAM/UCE/UBE protection via several means.
 .
 Sendmail includes *no* Mail User Agents (MUA), you'll have to
 pick from the plethora of available MUAs (mutt, vm, etc.)
 .
 This package supports REGEX, DB, NIS, NIS+, LDAP, DNS maps,
 and has enabled TCPWrappers, IPv6, LockFile, SMTP AUTH(SASL), STARTTLS(SSL).

Source package