There are two types of limit you can set for sending out cold emails:
Account limits
Campaign limits
For example, if you want one of your campaigns to send out 500 emails per day, while at the same time you want each account to only send 50 of those, you can do so by setting a campaign limit of 500 and individually setting a limit of 50 to each of your accounts, assuming there are 10 of them.
Campaign limits
You can set your campaign limit by going into your campaign settings:
Go to your campaign, then to Options
Scroll down to the very bottom to find the campaign's daily limit
You can only reduce the gap between your emails to make sure the intended volume of your email goes out per day which is optional.
Account limits
You can set your account limit by going into your account settings:
Click on the email account from the Email Accounts section.
Go to the Settings page and check "Daily Campaign limit"
The minimum wait time in the account settings allows you to set a time gap on each account level when using the same account in multiple campaigns.
You can set a minimum time gap for each account and the account will not send an email from any of the campaigns they are associated with until the sending gap (account level) gets completed.
FAQ
Q: Why is my campaign not sending enough emails?
A: If your campaign is not sending enough emails, please make sure that:
You have enough email accounts connected to this campaign to support the volume
Your sending account email volume limit is not set to fewer emails hence overriding the campaign volume limit.
"Time gap between emails" allows you to send enough emails in the specified time frame
You have enough new leads added to the campaign
Q: Will Instantly respect the account or campaign limit?
A: Account limits override the campaign limits, so if you have the campaign limit set to 500 and the account limit set to 30, assuming you connected 10 of the accounts to this campaign, it will be possible to send only 300 campaign emails per day, due to the set account limit.