Calling business logic in a factory is a code-smell, because it
usually requires the object to be saved into database, and may have
unintended consequences when the business logic is changed.
Also, this allows to just build a published procedure, without saving it
to the database.
Although we already ignore "invalid recipient" errors, a new type
of error recently popped: the mail service responds with
> Net::SMTPServerBusy '400 unexpected recipients: want atleast 1, got 0'
We want to also ignore this kind of errors.
