The reason it doesn't apply is because something is butchering the
whitespace. Whatever it is, it thinks it knows better than you do,
and is converting the tabs in the patch to a series of space
characters. Your email also appears to be using quoted-printable
encoding.
It looks like you're using git-send-email - and that should be fine.
It also looks like you're sending through a MS Exchange server...
My suspicion would be that the MS Exchange server is re-encoding
to quoted-printable and is butchering the white space, but that's
just a guess. I've no idea what you can do about that.