Currently the format from Maniphest mail notification of updates to a task is not very easy reading, and file attached cannot be download via mail directly.
Look to see if we can make the mail functionality better to read. Attached mail format from Redmine and Sharepoint for reference.
Current Maniphest Mail format:
{F186010}
Redmine mail format:
{F186012}
Sharepoint mail format:
{F186014}