@paulbaumgart Nothing currently, no. But you could use a service like Zapier or IFTTT to send emails into Slack. 

@SlackHQ Are there any OS X email clients that support dragging and dropping a message into Slack? Fwding emails to teammates feels so 2013.
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@SlackHQ@paulbaumgart To continue email conversations in Slack, I cut and paste the email as a text snippet. Works great.
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