I’m not sure but as far as I can remember (or at least about 2 years ago) I found a function to activate the subscribers without their needing to opt-in (even though a warning from Aweber would pop up). I lost about 70% of my subscribers in my very small list back then when I changed, but I’ve been able to grow it ten-fold since. And I used opt-in, because I didn’t want anyone to complain to me later.
There are drawbacks, however, and they are threefold: first, the program seems to be falling behind on the social media front. Second, AWeber is a little on the pricey side, especially for businesses with very small lists (1000 and under). Once you hit the 2500-subscriber mark, costs are more in line with industry averages. The company has no send-based subscription plan, which means if you have a large list but send infrequent emails, there are probably better choices for you. Third, the company makes its free trial unnecessarily burdensome by requiring a credit card. This would be a minor issue if not for the fact that customers have reported complications with canceling the service.
Finally, you can optionally include “automations” with your broadcast. Automations are a simple way to automatically add or remove tags when your subscribers do certain actions, like open the email or click on specific links. Adding and removing tags are important when creating segments, or subscriber groups, and triggering automated email campaigns.