Re-implement the way we handle mailinglist aliases

One-sentence description

Re-implement the way we handle mailinglist aliases

Why?

Decrease workload on server

Current implementation

All aliases are handled as separate mailinglists and synced like so. If an email gets sent to an alias of a mailinglist the message doesn't end up in the main mailinglist archive.

Suggested implementation

The alias should redirect incoming email to the main mailinglist without additions or archiving. This should speed up the syncing of mailinglists as well.