I just sent mass email to 300+ members on my list with no issues, took maybe 5 minutes to complete with no failures so this bug does not appear to be affecting all lists.
Are you using smtp option for sending mail?
I am away at the moment on a mobile device and cannot confirm, but check the join form template and you should see the limits.
Also looks like I will need to patch the error message style for 1.1
Thanks for the kind words :) always nice to hear, it's our customers that keep us having fun developing this product, and that translates into a better experience for everyone involved... including us!
Cheers