You should always try to build a list of subscribers in the long run. But until you have your list, you can use programs called safelists. Safelist is a program where you can join and send your e-mail ad to other members of that program. Each member must agree to receive e-mail promotions from other members so, there can not be accusations of spam.
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HOW DO SAFELISTS WORK?
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In order to send your e-mail ad to other members, you must earn credits. You can earn credits by clicking ad links in e-mails that you receive from other members. So safelists work on exchange principle. You read e-mail ads from other members and in return other members read your e-mail ads.
As safelists usually have thousands of members, who have the right to send you their e-mail ads, your inbox could get overloaded with e-mail ads. So you shouldn't use your primary e-mail address for safelists. You should find online e-mail provider that allows safelists and use one dedicated e-mail account just for that purpose.
Other downside is that your e-mail ad can get lost between many e-mail ads that other safelist members receive. But you can help this by using good subject lines for your e-mail ads and some other techniques, but this won't be covered in this article.
But even with those downsides, safelists can be useful tool, if used the right way. Safelists shouldn't be replacement to your own targeted list of subscribers, but they can supplement your advertising efforts.