I've been testing a batch of new emails, all of which are working out except for when viewed with the Office 365 client, which is doing something really odd: Any HTML links in the email body are being rendered so as to show the URL, with random added square brackets.

So,

<a href="URL">Link Text<a>

is being rendred as

[URL]Link Text

in the email body.

The only links that are doing this are the ones that contain tracking codes, so they do contain question marks. This is the only real differance between the links that dispaly broken and the ones in the same email that work.

Anybody got any ideas?