We've all received that email in which we and someone else are CCed in order to make an email introduction. Sometimes these are done blindly and work out well, but often they are done with the best of intentions yet can leave parties bemused and unsure of what to do next or why they were connected in the first place. There's a simple system that I recommend in order to make sure this never happens to you.
The Double Opt-In Introduction
This form of introduction signals to people that you not only took the time to connect them with someone meaningful, but that you gave your reasons and asked permission. Here are the steps:
Email both parties, separately, that you want to introduce. In this email tell them why you would like to introduce them to this person. Make sure that you aren't just saying something like, "Well, you both live in San Francisco and should get some beers." This provides neither party with any clue or direction, and in a very busy world, you're simply adding to their pile of to-dos, not giving them a meaningful reason to connect.
You may find in this process that they already know each other (great!) or that they can't connect because they have worked together in the past and no longer do or have some contractual obligation that doesn't permit them to develop a relationship with that person. You never know the reasons why, and the specifics don't matter. What does matter is that taking this extra step means you avoid egg on your face (and everyone else's).
When both parties say yes, then you can connect them. When you do, make sure to stress an uncommon commonality. Something that is unique and unusual that will connect them and start them down a path of communication that may lead to an in-person meeting. It can be professional: "Both of you guys are such advocates for Slack I feel like you work for them!" or fun: "I can't get him to stop talking about Westworld and how different the TV series is from the original movie!"
Building Your Social Capital
One of the best aspects of this form of introduction is what it says about you to the people you connect. Not only have you taken the time to ask permission to introduce them, but you've given a thoughtful connecting thread to make sure that the interaction will stick, rather than just twist in the wind and get lost with a thousand emails.
I would challenge you to try to do this at least once a month. The value that you create for others will come back to you, not just in the connections that they make because of you, but because of the process you follow in trying to add value to them: it's thoughtful and giving, and that's one of the best foundations for life and business.