How long should you pursue a potential customer?

In calling potential customers or recruits about three calls is enough if they do not make a commitment to follow through and purchase a product or join your program. Anymore than this can be considered harassment unless they tell you to call them again at a particular date. You may want to ask them if it is okay to call them again. As far as using emails make sure that the follow-ups are permission based such as them subscribing to a series of follow-ups to learn more about a particular product or opportunity. If you do not use permission based emails you may be accused of spamming. Make sure that there is some way that the potential customer or recruit can opt out of receiving emails. Another less used method of following up is by sending letters via U.S. postal mail also referred to by some as snail mail. I would suggest up to seven letters per prospect this way but this can get kind of expensive with the cost of postage these days.

Well, looking at the telemarketing industry I'd say there's no limit...but that's the reason why people hate telemarketers. I say notify them once, then notify them again after a little while, and if by the third or fourth time they still don't respond then consider them lost.