People put up with unwanted catalogs, credit-card offers, charitable appeals and other "junk mail" that clutters their mailboxes at home. We sigh about dead trees and toss it all away. Our e-mail inboxes, however, are a different story.

Consumers take a very proprietary view of their e-mail inboxes. Direct mail doesn't elicit the same "How dare they?!" reaction as unwanted e-mail. People feel strongly that they have a right to decide what e-mail they receive and what they don't. That's why your e-mail marketing communications must be welcomed and wanted. This also applies to new business contacts you meet at networking events. You may add them to your e-mail list, but only if you gain their permission first.

How Do You Ask for Permission?
Before we get to networking, let's review some list-building basics for permission-based e-mail. Both your website and your physical store should make it easy for people to "opt in."

Your website should have a prominent link or button for visitors to sign up for your newsletter and promotions. The right technology can facilitate signups. If you're embarking on your first e-mail marketing campaign, it's okay to send it to your pre-existing customers. Good marketing practice is to put a "permission reminder" at the top of your first e-mail communication: "You received this e-mail because you're a customer of Business XYZ. Click here to unsubscribe."

There are other great ways to obtain permission and e-mail addresses. You may have a guestbook or a fishbowl for business cards on your counter with a "Join My E-mail List" sign. You should encourage your staff to verbally ask customers to sign up. The more explicit your request for e-mail subscribers, the better. But that's not always natural or convenient, especially when you're out networking and prospecting for leads.

Business Card Bingo: Ask Now, Sell Later
Before- and after-hours events sponsored by Chambers of Commerce, BNI, trade associations and other professional networks are a good way to meet potential partners and customers. Networking is a lot of handshakes, elevator speeches and exchanges of business cards. It would be great to add all those people to your e-mail marketing list. But you can't just carry around a fishbowl labeled "Join My E-mail List."

So how do you turn that stack of business cards into subscribers? First, separate them into two piles. The first pile are people who asked for more information about your business. Asking for more information is very close to asking to be on your list. They're expecting you to follow up. Go ahead and e-mail them your Welcome Letter and attach a copy of your last newsletter or campaign. Show recipients what they'll receive in future mailings and give them an easy way to subscribe or unsubscribe if they prefer not to be on your list.

The second pile are people with whom you had social contact but didn't fully engage. They didn't ask for, nor do they expect, any follow-up. Those are the ones you need to ask permission to send them your e-mail newsletter or promotions. You can send those people a personal e-mail asking for their explicit permission to be added to your mailing list. Remind them about the event where you met, asking if they would like to subscribe to your e-mailing list. Tell them how subscribing will benefit them. If they sign up, great! If they don't, cross them off your list and cut your losses there.

Don't Let Those Leads Grow Cold!
A networking event isn't over when you grab your coat off the rack and head out to your car. You need to close the permission loop as soon as possible. If you found the networking event valuable and you met some great contacts, then don't let that go to waste. Follow up with new contacts as soon as you get back to the office. You can wait a few days or a week, tops, but if those business cards sit on your desk for months before you reach out, it's likely no one will remember you and they won't sign up.

Permission Isn't Just Polite...It's the Law
Please note: Shared affiliation isn't permission! Just because you have a directory of Chamber members doesn't mean you have permission to add those names to your e-mailing list. Prospecting isn't illegal; putting someone on your e-mailing list without asking and repeatedly e-mailing them is.

In other words, one-to-one communication is fine; one-to-many without permission isn't. Do reach out to fellow professionals with personal e-mail or a phone call, asking if they'd like to join your e-mailing list. Do not send a mass e-mailing to everyone in your business directory. That's spam. The federal CAN-SPAM Act protects consumers against unwanted e-mail. Read my article on "Creating Spam-Free E-mail" for tips on compliance.

So attend those networking events, collect those business cards, and build your e-mail marketing list. Just be sure to get permission before e-mailing your new contacts. Then you and your small business will be on everyone's "A-List."

Gail F. Goodman is the "E-Mail Marketing" coach at Entrepreneur.comand is CEO of Constant Contact, a web-based e-mail marketing service for small businesses. She's also a recognized small-business expert and speaker.