Rated 5 out of 5 stars

Great addon, Great work! I use it everyday.

I would to set some custom rules like:
-Next 8am (I write at night and most of the time, I want my mail to leave tomorrow morning )
-Next Business day 8am (I write on weekends and some emails should leave when business open)

Thanks

This review is for a previous version of the add-on (6.3.1).  This user has a previous review of this add-on.

Please read the user guide:

https://blog.kamens.us/send-later/

You can write functions to implement whatever scheduling logic you want. Some example functions which do things similar to what you asked for are provided. See this section of the user guide in particular:

https://blog.kamens.us/send-later/#dynamic