How to create groups <= 20

[TOzirsky]

Will someone please let me know what tools to use with Designer Desktop to take a file of 1000’s of accounts with greater than 20 email addresses per account and narrow it down to 20 email addresses per account using specific fields in the data set to narrow it down to the 20. And if the highest priority field has more than 20 email addresses then randomly select 20 email addresses and repeat for the next prioritized field until reaching 20 email addresses per account.
Thanks,
Tim

[TOzirsky]

It is okay with me if you submit as a weekly challenge.
Thanks again,

Tim