Revert "email: add support for Server Name Indication (SNI)"

This reverts commit 02684c911b4c035404a856bf145d2f616c1d0b08.

It's causing NPE because of socket.close (see https://android-review.googlesource.com/#/c/89135/3)

Change-Id: I5c524db1ae23e6a9b8852014b2f10332ff32de61