Update mail gem to 2.6.5

This should fix the extra backslashes in e-mail names as well as other things: https://github.com/mikel/mail/blob/master/CHANGELOG.rdoc#head

restored source branch sh-bump-mail-gem

changed milestone to %9.2

This should fix the extra backslashes in e-mail names

approved this merge request

merged

mentioned in commit ff400194

mentioned in issue #18251 (closed)