Currently users get emails, if a package was updated, if there are an owner or watch a project which is an owner. This is annoying: I get spammed by packages updates. I think I can manage this via herald, but it would be better, if we can manage the mail settings via preferences, so users can ignore single types of messages.
The following applications need modernizing before moving forward (they use `mailtags`):
[x] Audit
[x] Badges
[x] Calendar
[x] Countdown
[x] Differential
[x] Fund
[] Maniphest
[x] Paste
[x] Phame Blogs
[x] Phame Posts
[] Pholio
[] Phriction
[x] Phurl
[x] Ponder
[] Projects
[] Slowvote