@title Configuring Inbound Email
@group config

This document contains instructions for configuring inbound email, so users
may update Differential and Maniphest by replying to messages.

= Preamble =

This is extremely difficult to configure correctly. This is doubly true if
you use sendmail.

= Installing Mailparse =

You need to install the PECL mailparse extension. In theory, you can do that
with:

  $ sudo pecl install mailparse

You may run into an error like "needs mbstring". If so, try:

  $ sudo yum install php-mbstring # or equivalent
  $ sudo pecl install -n mailparse

If you get a linker error like this:

  COUNTEREXAMPLE
  PHP Warning:  PHP Startup: Unable to load dynamic library
  '/usr/lib64/php/modules/mailparse.so' - /usr/lib64/php/modules/mailparse.so:
  undefined symbol: mbfl_name2no_encoding in Unknown on line 0

...you need to edit your php.ini file so that mbstring.so is loaded **before**
mailparse.so. This is not the default if you have individual files in
##php.d/##.

= Configuring Sendmail =

Sendmail is very difficult to configure. First, you need to configure it for
your domain so that mail can be delievered correctly. In broad strokes, this
probably means something like this:

  - add an MX record;
  - make sendmail listen on external interfaces;
  - open up port 25 if necessary (e.g., in your EC2 security policy);
  - add your host to /etc/mail/local-host-names; and
  - restart sendmail.

Now, you can actually configure sendmail to deliver to Phabricator. In
##/etc/aliases##, add an entry like this:

  phabricator: "| PHABRICATOR_ENV=<ENV> /path/to/phabricator/scripts/mail/mail_handler.php"

...where <ENV> is the PHABRICATOR_ENV the script should run under. Run
##sudo newaliases##. Now you likely need to symlink this script into
##/etc/smrsh/##:

  sudo ln -s /path/to/phabricator/scripts/mail/mail_handler.php /etc/smrsh/

Finally, edit ##/etc/mail/virtusertable## and add an entry like this:

  @yourdomain.com	phabricator@localhost

That will forward all mail to @yourdomain.com to the Phabricator processing
script. Run ##sudo /etc/mail/make## or similar and then restart sendmail with
##sudo /etc/init.d/sendmail restart##