Skip cert verification

Problem/Motivation

We had a use case where skipping cert verification was needed when using TLS. The client's SMTP server had a certificate which the server could not verify.

The error we were getting was:

stream_socket_enable_crypto(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

Proposed resolution

According to https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting#updating-ca-... newer versions of the library can pass
options to the connection method.

Not sure if this is the approach we want, but here is a patch that brings in that part of the library. It's passed in as a Drupal variable and not configurable via Ui (not sure if that would make sense).

Remaining tasks

User interface changes

API changes

Data model changes