since Ubuntu 18.04 has reached feature freeze we started to think about 18.10.
One of the changes ahead is the dropping of the mail-stack-delivery package (part of dovecot).
This package was created a long time ago with the intend to simplify several steps of a mail server setup, for example to get a safe ssl secured default installation.
It is essentially almost only a postinst to set up some better defaults.
But the bit that I can derive from bug reports and such indicates that it is almost unused these days and has become an unused maintenance debt (it started to show it's age - no more matching e.g. recommended ciphers).
Furthermore the world has moved on:
- For encryption ssl is now default in dovecot-core
- In general the hosting your own mail service has become less attractive
- If users want to set up a mail server still they often look more for e.g. for Mail-in-a-box 
For all of these reasons we intend to drop the mail-stack-delivery package in 18.10
If there is a big love/consumption of the package we might have missed please speak up.
In that case we likely want to drop it from dovecot still, but community could take over maintenance in a separate package that lives in universe.
Software Engineer, Ubuntu Server