Refactor receipts to avoid SQLite3::RangeException in Rails 4.2
Inspired by
https://github.com/seankay/mailboxer/commit/f1096e2593708ff44c17e0bee1b9fb9566b31b49
Thanks @seankay!
Merge pull request #325 from mailboxer/refactor_receipts

Refactor receipts to avoid SQLite3::RangeException in Rails 4.2