How to avoid broken image urls with lines are ended with =?

Hi there!
I think that maybe the issue is like this: ??

Here an example, the html code of one image is:

<p><img height=3D"325" width=3D"502" alt=3D"" src=3D"http://apc=" /></p>

The email message header says:
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

And every line is having a hard line break at 72 characters, ending with =
And as you can see, the = is in the middle of the image url…
That is having issues in places like hotmail (webmail), and no idea wich others…

Adding define(“HTMLEMAIL_ENCODING”,“8bit”); to the config.php will work?
Any advice?