Running Phabricator on jessie has currently this blocker:
E: Unable to locate package php5-mailparse
on #debian there is the useful bot "judd" by the way, which tells us:
16:01 < mutante> and what could maybe replace it on jessie
16:02 < hwk> manual compile?
16:02 < missmbob> ,v php-mailparse
16:02 < judd> Package: php-mailparse on amd64 -- stretch: 3.0.1+2.1.6-12-gae1ef14-1; sid: 3.0.1+2.1.6-12-gae1ef14-1