Only 1% of e-mail marketers send an automated welcome message to new subscribers, according to Listrak. This is a shame because welcome messages have the highest open rates of all email campaigns, Listrack says. (via MarketingCharts).

Given that - and given the fact that a new subscriber is the most positive of all customer touchpoints there could be - it is not surprising that few marketers take advantage of another, more depressing customer touchpoint to reach out and communicate: when he or she unsubscribes.

Still, though, even at this point in the customer relationship it is worth doing one final outreach. That is because the relationship is not necessarily over, says Frank O’Brien, founder of NYC-based indie agency Conversation. "There has been a shift in the way email is being used now - it used to be an active promotion tool. Now it is becoming much more of a passive one. Just because someone is unsubscribing doesn’t mean he doesn't want your information. Instead, he is likely getting it from another source, like Facebook."

Of course, it really could be that the customer wants nothing more to do with you or your services. Or something between these two extremes. To find out, while not alienating the customer any more, follow these tips:

It doesn't hurt to ask why - and to offer to send e-mails less frequently.

First of all, says Carissa Newton, director of marketing for Delivra, honor the customer's request immediately. But before the unsubscribe process is complete ask them if they want to change their preferences instead. "For example, take them to a profile center with a message centered around asking them if they would simply like to change their preferences, frequency, etc. "If they are still set on unsubscribing, let them do it with a simple click at the bottom. This is not the time to require them to enter any additional information."

Once that is submitted, she says, either send a confirmation page with a quick fill-in box asking why he or she is unsubscribing or send one last follow up e-mail with the confirmation and a survey link. "While you want to make it simple and easy, it can't hurt to ask why. Chances are that someone will give you feedback that you could use to improve your program moving forward."

Be graceful.

Send a thank you note for their past patronage, is Vindicia SVP Sanjay Sarathy's advice.

Then, make yourself available.

Marketers have learned to increase their footprint in the social communities of which that prospect is a part, says Jake Wengroff, global director of corporate communications at Frost & Sullivan. " Syndicating content and linking to the usual suspects - Twitter, Facebook, LinkedIn, SlideShare etc  - can facilitate this process so that the opt-out will sooner or later stumble upon relevant, compelling content from the company."

Also see in this special report: Read Digital Body Language to Stop an Unsubcribe and One Final Attempt to Get Them to Re-engage.