Can Facebook ban you for using Sendply? Of course. They can ban you for any reason at anytime they wish. The only time I’ve had an issue has been a few times Facebook has temporarily blocked me (24-72 hours) from sending Friend requests because, well, I got stupid and sent them too fast.
That’s why we have speed and quantity limitations YOU can set. You can set a total number of requests to send within a day, and how much time to wait between requests. What settings do we recommend? I don’t send requests with less than a 3 to 5 minute interval between them, and I typically limit it to between 50 to 100 per day.
Now, obviously, we don’t have any inside information into what Facebook’s internal limitations are, so we can’t say that you’ll be fully protected if you stick to those limits. But they’re what I stick to, and my Facebook account is doing just fine. YOU are in full control of the risk level you are comfortable taking. Stay low risk and you should stay under the radar.