User Agent: Mozilla/5.0 (X11; Linux i686; rv:36.0) Gecko/20100101 Firefox/36.0 SeaMonkey/2.33.1 Build ID: 20150321194732 Steps to reproduce: I receive a mail with UTF-8 encoded header lines. User-Agent: Mozilla/5.0 (X11; Linux i686; rv:36.0) Gecko/20100101 Firefox/36.0 SeaMonkey/2.33.1 Actual results: SeaMonkey shows the following: From: =?UTF-8?B?w5Z0dsO2cyBQw6l0ZXI=?= via RT <...> Expected results: The name of the sender should be decoded: From: Ötvös Péter via RT <...> I checked the mail header and found that the line in concern has quotation marks in it: From: "=?UTF-8?B?w5Z0dsO2cyBQw6l0ZXI=?= via RT" <...> If I remove the quotation marks the name is displayed correctly. This is annoying since - Thunderbird (Icedove) 31.6 has no problem to encode the header, - I can't remember that the former versions of SM showed this problem.

This might be fixed by Bug 1165612