Like all introductions, when introducing two parties through email, a "connector" should ensure the introduction is beneficial to both parties. To do so, the standard practice is to get both parties to opt in. That is, you ask both parties if they would like to be introduced to the other person before you put a burden on their inbox.
There’s nothing more unpleasant than receiving a random email, saying you have a mutual acquaintance that provided your contact information. It’s an invasion of privacy and puts the person in an uncomfortable situation of needing to be rude in ignoring the emails or declining to speak with them. So, when in doubt, play it safe and do double opt-in emails. That said, if time is of the essence, there are a few situations where it's to make blind introductions.
1. You are confident in the introduction.
If you’re 100 percent sure the two people will want to speak with each other, it’s OK to make a non-double opt in email introduction. For example, if you’re introducing someone to a potential client or customer, there’s an extremely high probability that they will at least take a meeting.
A few weeks ago a friend emailed me saying he needed to hire someone to help his company with bookkeeping. I have another friend who helps companies with bookkeeping. Since I know both friends pretty well, I made the email introduction without getting opt in from the bookkeeper. I was 100 percent confident that the bookkeeper would at least want to take a meeting with my friend because it could lead to him making money.
2. You have a certain comfort level with the other person.
If you are on a “free to intro” basis with someone, it’s OK to make a blind email introduction. There are only a handful of people I have a level of comfort with that I would send them an email introduction without opt in. They have told me that they will accept any introduction I want to make for them or I have told them they can introduce me to people without making introductions. For a few people it is simply implied and unspoken, like co-workers.
The “free to intro” phase can also be temporary. For example, a friend was hiring a business development person and said I was free to introduce him to anyone I felt was qualified.
3. You realize the individual is extremely busy.
I know a few people who are both great connectors and extremely busy. They don’t always make double opt-in email introductions, as it would simply take up too much of their time. I don’t mind getting blind email introductions from these super connectors, because I know how busy they are.
There have times when I have been so busy and focused on a given project, that I also make blind introductions. In this case, I make sure to let the person who asked for the intro that I am going to make a non-double opt-in introduction and when I make the email introduction I let it be known that I’m too busy to get double opt-in, and, if they don’t want to talk, they should feel free to ignore my email.
While it’s not the most polite thing to do, if you are extremely busy, and you are pretty comfortable with the people you are introducing, it’s fine to make a non-double opt-in email introduction as long as you apologize and let both parties know the situation