So while configuring a new instance today, it struck me how many times I have to put some version of the domain where my instance is hosted into the configuration. By my count, that domain appears no less than 12 times.

• metamta.reply-handler-domain
• metamta.default-address
• metamta.domain
• metamta.maniphest.reply-handler-domain
• metamta.maniphest.public-create-email
• metamta.paste.public-create-email
• metamta.pholio.reply-handler-domain
• metamta.macro.reply-handler-domain
• metamta.differential.reply-handler-domain
• metamta.diffusion.reply-handler-domain
• metamta.files.public-create-email
• phabricator.base-uri

It would be nice to have to set my domain in only one place - I'd imagine that for most installs, these values will be largely the same.

For the properties above that are public-create-emails, I'd suggest having a separate configuration item that's something like metamta.paste.public-create-email-user, with a sensible default (like 'paste') that would construct the email address configured-email-user@reply-handler-domain, and perhaps have a separate flag that indicates if this functionality is enabled or not.