@phyks, mind to have a look? Many things are poorly coded in this MR (no translations, raw handling of emails), but this was enough for me to work :)
- the emails get a pretty bad spam score because they don't have a Date header...
- ... as well as a MessageId header.
- we could probably do some better display in the HTML case
- also, maybe we don't want emails on notifications, but email every N hours if there's at least one new flat, or an email every time there are at least N new flats or M hours have passed.