In order to enable single-opt-in for Aweber when emails are being added through the API (by a 3rd party product like UpViral), Aweber needs to manually approve your account to do that.
So, if you want to have your account and your lists enabled for this, all you have to do is contact AWeber through their online form, or email email@example.com.
Tell them you want to enable single opt-in for your lists for use through their API. AWeber will then either approve or deny your request after they review your account.
How to get your support tickets resolved faster
Statistics have shown us that the more you tell us when you report an issue, the faster we solve that ticket. So...
1 - If you have screengrabs, please include them. A picture is worth a thousand words.
2 - If you have recorded a video showing the issue you're having, please include that as well. A video is worth a million words.
We recommend a free service called Loom for creating these videos. (this is a link to https://www.useloom.com/)
3 - To speed up ticket resolution, follow these useful tips How to Write the Perfect Support Ticket (That Gets Results Fast)