phpList rate limit and massive amount of send attempts


I have a question - I have a mailing list with about 3,500 subscribers and have been using phpList for a while without a lot of problems.

Recently, the hosting company decided to unilaterally reduce the hourly rate of emails that can be sent by my domain to 1000 (from 1800 before). So in the next campaign, phplist tried to send 1600 emails/h as it should but was prevented from sending 600, because of the new rate limit.

Strangely, though, instead of 600, phpList attempted to send 8700 emails in that hour of which 7700 were rejected. In the next hour, similarly, 1000 were sent, and 7700 attempts were rejected, after that the last 900 Emails in the queue were sent, but phpList still made 6532 attemps to send.

What is happening here? I would assume that even after being rejected at 1000 emails phpList would retain the configured rate of 1600 send-attempts per hour? Why the sudden increase in attempted emails?

Thanks for any explanation!