[pkg-gnupg-maint] Bug#1025782: gpg-wks-server not build with sendmail

[Konstantin Zangerle]

Package: gpg-wks-server
Version: 2.2.27-2+deb11u2

Usage of gpg-wks-server as outlined in https://wiki.gnupg.org/WKS
Especially the part about the procmail configuration.

When using gpg-wks-server to send confirmation requests, gpg-wks-server
requires a working sendmail.
The constant NAME_OF_SENDMAIL is set during the ./configure call.
The constant is used in tools/send-mail.c to send mails to verify the
request. I suggest building gpg-wks-server with the configure option
--with-mailprog and add a dependency to mail-transport-agent.

Relevant log lines:
gpg-wks-server: error running '': probably not installed
gpg-wks-server: running '' failed: Configuration error
gpg-wks-server: command failed: Configuration error