Just because your email list is an online marketing tool, it doesn't mean that you only have to solicit emails online! If you have a retail location, you can collect emails when customers purchase or visit the store or other location. If you market by attending festivals or concerts, you can collect emails at those locations. Offering to raffle off a prize but requiring an email on the raffle ticket can also be an effective way to grow your email list. Of course, you'll have to dedicate the time to retyping all of the emails that you collect into your system, but it's often worth it. Don't overlook offline opportunities to grow your email list.
You can use this strategy to your advantage and increase your email list by giving people an incentive in return for their email. The giveaway could be free access to an e-book, a report, a gift hamper, or perhaps a lucky draw where people enter their emails and get a chance to win. A tantalizing offer is all you need for people to comply. For example: