Pass option: "enable_tls true" to enable_tls (SMTPS)
New gem complains:
ERROR:  While executing gem ... (Gem::InvalidSpecificationException)
    duplicate dependency on fluentd (>= 0), (>= 0) use:
    add_runtime_dependency 'fluentd', '>= 0', '>= 0'
Merge branch 'fix-duplicate-dependency' into enable-tls
Merge pull request #10 from mash/enable-tls

Pass option: "enable_tls true" to enable_tls (SMTPS)