Corinna, Christian, Daniel, Pierre,
Because MTAs must be user-configured, and we certainly don't want to
lose the selection during package upgrades, the alternatives cannot
be handled in package postinst/prerm. I think the only way to make
this work is for each MTA config script to handle these instead by
including the following snippets in the respective MTA config scripts.
Please review this carefully in case I missed anything.
...
postfix:
========
/usr/sbin/alternatives --install /usr/sbin/sendmail mta
/usr/sbin/postfix.exe 0 \
--slave /usr/lib/sendmail mta-sendmail /usr/sbin/postfix.exe \
--slave /usr/bin/mailq mta-mailq /usr/sbin/postfix.exe \
--slave /usr/bin/newaliases mta-newaliases /usr/sbin/postfix.exe
/usr/sbin/alternatives --set mta /usr/sbin/postfix.exe