These are the addresses we deliver mail from when passing filtered mail on to your server.


Add them all to your firewall, mail filter, or hosted-platform allowlist so our deliveries are accepted.



As of 2026-08-01 we are beginning to slowly ramp up Email Gateway and MX Backup deliveries via the address blocks 104.232.45.16/29 and 204.27.244.16/29

If you are experiencing mail delivery delays please double-check that your destination server(s) are configured to accept mail from these ranges. 


United States

  • 104.232.45.16/29— if your firewall does not accept CIDR ranges, add these eight addresses instead:
    • 104.232.45.16
    • 104.232.45.17
    • 104.232.45.18
    • 104.232.45.19
    • 104.232.45.20
    • 104.232.45.21
    • 104.232.45.22
    • 104.232.45.23
  • 54.148.30.215
  • 54.148.222.11
  • 54.148.229.97
  • 54.149.36.10
  • 54.149.154.28
  • 54.149.205.143
  • 54.149.206.185
  • 54.186.22.84
  • 54.186.27.61
  • 54.186.60.165
  • 54.186.172.23
  • 54.191.151.194
  • 54.191.158.99
  • 54.191.214.3
  • 54.191.214.36
  • 54.68.193.51


Europe

  • 204.27.244.16/29— if your firewall does not accept CIDR ranges, add these eight addresses instead:
    • 204.27.244.16
    • 204.27.244.17
    • 204.27.244.18
    • 204.27.244.19
    • 204.27.244.20
    • 204.27.244.21
    • 204.27.244.22
    • 204.27.244.23
  • 52.28.30.98
  • 52.29.118.68
  • 52.29.142.239
  • 52.29.144.204
  • 52.29.162.96
  • 52.58.5.29
  • 52.58.7.81
  • 52.58.7.120


Do I need both regions, or just one?

It depends on the MX records your domain points at.

If you use these MXes:... then add these sets:
a####.mx.mailhop.org
mx1.mailhop.org
mx2.mailhop.org
mx1.mailhop.us
mx2.mailhop.us
mx1.mailhop.co
mx2.mailhop.co
mx1.mailhop.co.uk
mx2.mailhop.co.uk
United States and Europe
mx1.us.mailhop.org
mx1.us.mailhop.us
mx1.us.mailhop.co
mx1.us.mailhop.co.uk
United States
mx1.eu.mailhop.org
mx1.eu.mailhop.us
mx1.eu.mailhop.co
mx1.eu.mailhop.co.uk
Europe


We use four top-level domains across two DNS providers so that a problem at one registrar or DNS provider cannot take your mail offline. The domain ending (eg: .co.uk or .us) is not related to the filtering region; only the us or eu label in the first subdomain position sets the region, and where there is no such label your mail uses both.

If you have chosen a single region, we will not move your mail to the other one, so you only need that region's addresses.
If you are not sure which you use, add both — that is always safe.

For more on choosing a region, see Worldwide Email Filtering Clusters MX Record Settings.

Using Google Workspace or Microsoft 365?

A firewall rule may not be enough. These platforms keep a separate list of trusted inbound sources, and mail from us can still be rejected if our addresses are not added there as well:

Outbound SMTP customers

The addresses on this page are for inbound delivery only. They are not required for, and do not apply to, the Outbound SMTP service. See IP Addresses of SMTP Servers.

Document History


30 July 2026

Changed:

  • 104.232.45.0/24 narrowed to 104.232.45.16/29
  • 204.27.244.0/24 narrowed to 204.27.244.16/29

Removed:

  • 54.69.62.154
  • 54.69.130.42
  • 54.148.219.64
  • 54.149.155.156
  • 54.149.210.130
  • 54.186.218.12
  • 54.200.129.228
  • 54.200.247.200
  • 54.213.22.21

Sections renamed from ORE1 / ORE2 / ORE3 / EU1 to "United States" and "Europe".

8 January 2021

Added:

  • 204.27.244.0/24


1 January 2020

Added:

  • 104.232.45.0/24