#39 mail queueing to retry should smtp_server be unreachable

[Nick Silkey]

Users experience "Unable to send email notification to user@domain.com: [Errno 111] Connection refused. This has not impacted the file being shared with the user, but you may need to notify the user manually that a file has been shared with him or her." should smtp_server be unavailable. It would be sweet if filelocker would retry transmission to smtp_server when an issue is encountered.