A few months ago I had a bit of a heated email argument with a fairly well-known marketing guru whose newsletter I subscribed to.

I won't mention names as the point of this post isn't about criticising others – it's about something I believe to be vital to succeed in business development: authenticity.

The argument started when I received an email from the guru sent from a hospital waiting room in a few moments he had spare waiting for his wife to give birth. His email said he had to be quick (for obvious reasons) but wanted to make an offer on one of his new products.

Nothing wrong with that, per se. In fact I believe it's good thing to share insights into your personal life with your community. It deepens your relationships – rather like the way you'd share personal information, ideas and hopes with a close business partner or one of your best clients. Your very best business relationships go beyond purely business.

The problem was that I received the same email 3 times over a 3 month period.

I emailed the guy, and he said he'd had a problem with his email system. OK, fair enough. No one has perfect grasp of their technology. I'm prepared to believe it was a genuine mistake that multiple copies were sent out.

But then I noticed that the emails were actually all a little different. They had slightly different headlines.

In other words, he'd been split testing the headlines.

Now split testing headlines is a good marketing practice in normal circumstances. But when your email is supposed to be something you rattled out quickly when in a hospital waiting room it actually leaves a rather nasty taste in the mouth.

Far from being the spur of the moment message it purported to be, this was a calculated marketing tactic. And it left me feeling manipulated.

Here's the deal: had this been a normal marketing email then, of course I'd have been perfectly cool with headlines or anything else being tested, optimised or whatever. Why shouldn't the marketer try to maximise the response they get?

But this was an email that purported to be a spur of the moment outpouring. His email personalised things – brought me into his world. It made me feel closer, as if I was sharing his experience.

For me then to discover that the email had been a calculated construction left me feeling used.

And that's the thing. The most powerful marketing & sales approaches are the ones that bring us closer to our clients, that deepen our relationships.

But they must be genuine.

Deepening a relationship can't be one-sided. You can't pretend to open up to someone, but really put a tight filter on what you say. You can't encourage a client to be frank and honest with you if you're not going to be frank and honest with them.

If you do try to manipulate, you'll be found out. It may not be as obvious as a split-test headline on a supposedly personal message: but people will discover your manipulation.

If you can't be genuine – then stick to more impersonal forms of business development: advertising, factual messages, value propositions.

But if you want to build deep. long lasting relationships with clients, you must, must be authentic.