phabricator 92d520cdc2160b95f03b89c10ebf0c9edaf7c547 (Mon, Feb 27) arcanist 467dc3ae4286df6d42730d472b7b52d3afa33ec5 (Mon, Feb 27) phutil 6c902414c30dfaad64f24b3bc950857cebbcf8fe (Mon, Feb 27) libtwitter 65e64977fd93383256ed3a0292aaf9ef1502bb9c (Wed, Feb 15)
- Set metamta.one-mail-per-recipient to false
- Create a revision and add hundreds of reviewers (enough such that their emails exceeds 989 characters)
To: field in revision emails contains a comma separated list of email addresses for all reviewers, with every email correctly formatted
To: field in revision emails contains comma separated list of email addresses, but adds a newline every 989 characters. So at around the 989 character mark, the to: field looks something like
..., email@example.com, sba firstname.lastname@example.org, email@example.com, ...
We can privately send you a raw email example if that helps. This is consistently happening to revisions with a large number of reviewers.