Where is the number of emails to load option that is on the S3 on the S6?

[AC Question]

Where is the "number of emails to load" option that is on the S3 on the S6

To stop imap emails constantly re downloading emails when deleted the solution on the S3 was to set the "number of emails to load" to Total. Where is this option or how is it dealt with on the S6 as I have the same problem with this now...???