&lt;html&gt;&lt;head&gt;&lt;meta http-equiv="Content-Type" content="text/html; charset=utf-8"&gt;&lt;/head&gt;&lt;body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""&gt;<div>Today I received an email with (raw) subject line</div><div><br></div><div><div>Subject: =?UTF-8?B?8J+Pi++4jw=?= A SALE to boost your</div><div>&nbsp;=?UTF-8?Q?workout
?=</div></div><div><br></div><div><div>When displayed in Emacs in either unthreaded or tree mode, “^M” appears after the word “workout”, and the displayed line is split into two, like this:</div><div><br></div><div>&nbsp;Today 07:12 &nbsp;Jabra &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;🏋️ A SALE to boost your workout^M</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(important inbox)</div></div><div><br></div><div>It would probably be a good idea to check for, and remove, carriage return characters in the subject line.</div><div><br></div><div>(Note that the message displays fine in the default threaded mode.)</div><div><br></div><div>Richard Stanton</div><div><br></div>&lt;/body&gt;&lt;/html&gt;