User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; cs; rv:1.8.1.12) Gecko/20080201 Firefox/2.0.0.12 Build Identifier: 2.0.0.12 (20080213) This form of "From:"-line in e-mail: From: =?iso-8859-2?Q?Ing._Lubom=EDr_Kuchynka=2C_Tepeln=E1_=E8erpadla_AC_Heating?= <LKuchynka@ac-heating.cz> is unfortunately interpreted as two e-mail addresses because of the char "2C" (comma) involved and quotation marks (22) omitted. It is not possible to reply to such an e-mail because Thunderbird adds two addressees into the compose form which are naturally not valid. Reproducible: Always Steps to Reproduce: 1. Receive an e-mail which contains the line cited above or a similar one without quotation marks. 2. Try to reply to such an e-mail. 3. Thunderbird thinks it should reply to two addresses simultaneously. Actual Results: Wrong interpretation of one address. Expected Results: Right interpretation of the address even if the quotation marks are missing.

DUP of longlived Bug 254519.