Now that we support email aliases, we have to be careful when going from
an email address to a domain that we assume we can use to get a Realm
object for. When we care about the Realm's domain, we want to follow
any RealmAliases that exist for a certain domain.
When we just care about the original email address domain itself,
for comparison or other purposes, use split_email_from_domain
This removes the ambiguity of having to decide when to use
email_to_domain + RealmAlias or just email_to_domain
(imported from commit 0e199495502d946ce2e1aae56263e7e8665be4ed)
We don't really take good advantage of the parallelism anyway (though
it is very useful if you want to make 10000 messages, we don't do that
often). If we decide we need that functionality, we can figure out
what the right way is to do threads with this stuff.
(imported from commit 98aa4b54fab6fd437b7c7ac0c3c7e658d2f8cb33)