The short answer is, never. Unless the prospect asks you to stop contacting them.
Suppose you get started with a prospect and everything is moving along fine. You’ve had some calls, done some emailing, and even sent some samples. Then, nothing. They don’t respond to emails. They don’t take your phone calls or return your messages. You hit a wall. Do you give up?
If it were me, the answer is no. You never know what the circumstances are. You might just need to wait out a situation until the prospect is ready. Possible reasons for the lack of response could be a budget problem, no current needs, a new boss, the person was on an extended medical leave, etc. What do you do, then, when you don’t know what’s going on?
I believe you should just be yourself. How comfortable are you with the prospects that have gone silent? Have you met them in person, by phone, or via the internet? Did you start to build rapport with them? If you have, then you have an opportunity to try a different type of email or phone call to possibly reopen the dialog. For example, one time I sent an email with some self-deprecating humor to someone who was not responding to me. (This works even better with old clients, too, who don’t respond anymore.) NOTE! YOU HAVE TO KNOW THE PERSON A LITTLE BIT TO GO THIS FAR WITH THE HUMOR SO THEY GET IT AND AREN’T OFFENDED! Something along the lines of:
“Oh, I get it. You don’t love me anymore. I haven’t heard back from you lately, so I guess it’s over and you found somebody new.
“Just kidding! Seriously though, if I’ve done something to cause our growing relationship to come to a halt, can you let me know so I can make it right? I choose clients like you carefully because I consider you one of my friends. Can we talk?” (and then throw in some dates and times you are available for a call)
Sometimes just picking on yourself a bit and lightening up, trying to get a laugh, can get the dialog going again. There are so many factors that can interfere with the sales process! We cannot know them all unless the prospect is telling us about them. Today, more than ever, doing sales with prospects is about building a relationship, not just selling stuff. Stay with the relationship as long as you can. Until they tell you to stop contacting them, there’s always hope they might yet convert.
Anther possibility you have to consider is that someone else is now your target, that the person you WERE working with left that job and didn’t tell you. People change jobs a lot! If that’s the case, you have to start over with the new person. You can call or email to ask your prospect that question point-blank so you know where you stand. “Are you still the contact person responsible for promotions and branded wearables at your company/organization?” That might get a reply because it’s an easy yes or no answer. Anything to get a basic response and get them started talking to you again.
Unless you have a darn good reason to abandon the relationship, don’t. Just stay friendly and stay in front of them on a regular in a subtle way. Send occasional emails, samples, maybe give them a call now and then. In other words, keep them in a drip campaign.
Make most of those contacts things that could help them. Don’t make them all about selling stuff. For example, if you are contacting an HR person and you read an interesting LinkedIn article on HR, send it to them telling them that the article made you think of them and you thought they might find it helpful. That kind of thing. Add value to the relationship.
Until a prospect closes the door and asks you to please stop contacting them, continue to show how you can be a valuable partner to them over the long term, and hopefully one day soon you’ll enjoy the fruits of your efforts when they convert to clients. If nothing else, maybe you’ll at least make a new friend or get a referral that pays off.