Update with initial response & Blocking Open Relay#1

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hotdang-ca wants to merge 6 commits into

ralphholzmann:masterfrom

hotdang-ca:master

Commits on Oct 2, 2019

Update with initial response and PTR record required by modern SMTP senders
James Perih
committed
Support for blocking open relay.
James Perih
committed
Change to switch and cleanup logic; mark the global constants
James Perih
committed
Remove Pipelining feature, as we don't yet support it completely.
James Perih
committed
Update readme.
James Perih
committed
Update readme.
James Perih
committed