Problem email renew - IP range for firewall

Dear all, I have a problem with not receiving renewal emails, I checked that there is a blockage in the firewall, I wanted to know which IP ranges need to be released for correct operation.

Thank you for the help

Looking at the language you've written your post in, I'm assuming it doesn't need to be in the Portuguese section of the Help category. Therefore, I'll move it to the regular Help category.

We use a third-party email service provider (ESP), currently Mailchimp Transactional, to send expiration reminder emails.

Could you check which IP ranges or URLs should be allowed on the firewall?

Please keep in mind that these IPs (or our ESP) could change at any time.