If you send an email to a group of people at a company, or, if contacts on your list are using the same domain as your “From” email address, it's possible that your communication will not be accepted by the company's email firewall.
In order to get your messages into the inboxes of these contacts, we recommend working with their IT team to add the IP ranges listed below to a safe sender list.
| CIDR | Start of range | End of range |
| 173.236.20.0/24 | 173.236.20.2 | 173.236.20.254 |
| 192.92.97.0/24 | 192.92.97.2 | 192.92.97.254 |
| 52.128.40.0/21 | 52.128.40.0 | 52.128.47.255 |
| 217.8.118.0/24 | 217.8.118.0 | 217.8.118.255 |
| 103.229.233.0/24 | 103.229.233.1 | 103.229.233.255 |
Note that some transactional messages from ActiveCampaign may be sent from Postmark. For example password reset emails, login verification emails, etc. Learn more about Postmark's IP ranges.