To share a little background, our marketing automation system does have a limit to the number of emails a person can receive: max of 2 per day; 5 per seven days; and no limit to operational emails. Operational emails are things like a signup confirmation, EE trial license key & initial download instruction.
There are a certain periods of time that have the potential to create a "perfect storm" of emails to be sent/received in short succession.
Example of "perfect storm": If a person signs up for GitLab and download an EE trial the day or two before the bi-weekly newsletter email is sent, they could receive 3 operational emails and 1 marketing email in the first 24 hours.
Please let me know if you have additional questions or if I can explain something more clearly.