https://tools.ietf.org/html/rfc5322#section-3.3 specifically allows setting the -0000 offset for the timezone on a sent message to hide the localtime of the sender. Implementing a (hidden) preference to set this timezone would help preserve the (locational) privacy of sender when emails are sent e.g. over Tor. No information required for proper delivery of email is lost, given that the email still retains a proper UTC timestamp. For users in the United States, the date-time header is part of the metadata retained by the NSA, therefore keeping this metadata to a minimum is good for personal privacy (along with PGP encrypted mail).
Created attachment 1669 [details] Possible implementation with hidden pref. Documentation of new hidden pref to be done after code is settled ;-)
Changes related to this bug have been committed. Please check latest Git and update the bug accordingly. You can also get the patch from: http://git.claws-mail.org/ ++ ChangeLog 2016-08-22 19:09:03.170296681 +0200 http://git.claws-mail.org/?p=claws.git;a=commitdiff;h=c5a2e03b3c0899883e3f560e0d25dbd0bc6e8c74 Merge: 143d263 f4e8599 Author: Colin Leroy <colin@colino.net> Date: Mon Aug 22 19:09:02 2016 +0200 Merge branch 'master' of file:///home/git/claws http://git.claws-mail.org/?p=claws.git;a=commitdiff;h=f4e859902a0541db982248ee4a59901e0568d381 Author: Ricardo Mones <ricardo@mones.org> Date: Mon Aug 22 19:07:36 2016 +0200 Document the new hidden preference 'hide_timezone' http://git.claws-mail.org/?p=claws.git;a=commitdiff;h=3a89a270fcad59901d8fcdc901ac03523c6aeb03 Author: Ricardo Mones <ricardo@mones.org> Date: Mon Aug 22 19:02:47 2016 +0200 Fix bug #2975: Implement setting -0000 timezone to hide sender localtime This adds a new hidden preference, namely 'hide_timezone', that sets the timezone of date fields sent over the network to the unknown timezone value as specified in RFC 5322 §3.3. Default value is false (i.e., send available timezone information).