Improving PR#6

Improving PR #6

It is not necessary to confirm smtp protocol by providing the
requiresTLSUpgrade flag.

Added requiresTLSUpgrade to SMTPClient

Thanks, @brycesteve for PR #6!

Allowing caching build

3.0.1

Allowing caching build.

Upgrading to Swift 4.0

3.0.0

Upgrading to Swift 4.0

Fixed ISS-522

1.1.7

ISS-522 Fix

ISS-523

1.1.6

ISS-523

Fixing ISS-523 by improving Message-Id generation.

Thanks @LeAnne

Fixing ISS-521 / ISS-522

Thanks, @Leanne Lis!

Adding debug header.

1.1.3

Adding debug header.

Patching Linux Pointer Unwrap on Swift 3.1

1.1.1

Patching linux pointers