This should make it easier to track down how the incoming email was created, which is one of four locations:
The POP3 poller (which picks up reply via email replies)
The admin email controller #handle_mail (which is where hosted mail is sent)
The IMAP sync tool
The group SMTP mailer, which sends emails when replying to IMAP topics, pre-emptively creating IncomingEmail records to avoid double syncing
Adds the settings:
raw_email_max_length, raw_rejected_email_max_length, delete_rejected_email_after_days.
These settings control retention of the "raw" emails logs.
raw_email_max_length ensures that if we get incoming email that is huge we will truncate it removing uploads from the raw log.
raw_rejected_email_max_length introduces an even more aggressive truncation for rejected incoming mail.
delete_rejected_email_after_days controls how many days we will keep rejected emails for (default 90)
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
