This is a safety measure to protect your sender reputation. Google uses various indicators to judge if a sender is legitimate or is to be considered a spammer. There are various do’s and don’ts regarding email content that we discuss in other topics, but sending frequency is also a factor.
ProspectSafari imposes a throttle on the number of emails you send per hour and per day and inserts a minimum delay between each email send. These limits are entirely under your control (click on the Integrations menu) but are preset to good, safe practice. This means if you have a burst of activity sending emails to a bunch of prospects, they will be spaced out over the next few minutes and hours in order to avoid spam flags. This is all managed in the background so you can get on and be more productive.