Dropblank, nodropblank Channel Options

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Strip illegal blank recipient headers (dropblank, nodropblank)

In RFC 822 messages, any To:, Resent-To:, Cc:, or Resent-Cc: header is required to contain at least one address - such a header may not have a blank value. Nevertheless, some mailers may emit such illegal headers. The dropblank channel option, if specified on a source channel, causes the MTA to strip any such illegal blank headers from incoming messages. nodropblank disables this action and is the default.