To set a number of emails to be sent by Closely go to Accounts -> Account settings -> Daily emails limit. Please find our recommendations below

The daily limit number is set to 50 emails by default. The maximum number is 200 emails per day.

You are free to start with a higher number than 50 emails, however, if you have never run any bulk email campaigns from your email account, this might look suspicious and your account can be suspended for a period from 1 to 24 hours.

Here is what Google says: https://support.google.com/a/answer/166852

Microsoft is more strict in this matter: https://support.microsoft.com/en-us/office/sending-limits-in-outlook-com-279ee200-594c-40f0-9ec8-bb6af7735c2e

The maximum number of recipients you can add to a Closely outreach campaign is 5000. The number of emails in a sequence is not limited.