1. Is the listing site free or paid for?
2. How does it rank in Search Engines.
3. How frequently does the list send out the e-mails?
4. What types of listings does it allow?
5. Is it owner/creator-managed?
6. What additional perks does the list offer?
7. How long has it been in successful safe-listing business?
8. How favorable are the testimonies of users?
9. How many members are registered on the site?
10. How convenient it is to use the lists?
11. Does it mail only to its registered members?
12. How large is its e-mail addresses bank?
With these considerations, you can make informed-judgment about the quality of safe-lists.