SEPPmail Cloud DE instance: additional IP ranges from 2026-04-01 10:00 CEST to 2026-04-01 12:00 CEST

The extension setup of SEPPmail Cloud DE instance is about to go live. With added performance, geo redundancy and hoster redundancy we are ready for future growth. In early April traffic will start with a few selected NFR partner domains, before gradually going into production with all customers once the new IP addresses have warmed up sufficiently.

The oncoming changes should have no influence on customer experience. However, we advise to perform a few checks to ensure mail flow is not affected by configurations tightened to only the current IP addresses of SEPPmail Cloud.
For all M365 customers: check that certificate based connectors are used to receive mail.
For all other mailhostings: no firewall rules should block mail traffic to and from our IP ranges. Please ensure traffic to and from 37.49.152.128/28 and 2a04:d480:4400:11::/64 are permitted.
Inline outbound customers: ensure SPF include _spf.de.seppmail.cloud is used.

Manual intervention on customer side should only be required if:
SPF record was built manually instead of using our include. In such case please add the new IP ranges.
IP based connectors or firewall restrictions. In such case either allow all our IP ranges to connect to Port 25.

Inline customer’s outgoing mail will additionally be sent via 37.49.152.133 and 2a04:d480:4400:11:200:5eff:fe00:111
Parallel customer’s incoming and outgoing mail will additionally be sent via 37.49.152.134.
No manual intervention on customer side should be necessary unless some firewall restrictions would prevent access to port 25 of those IP addresses.

Inline customers MX records will be extended by additional addresses 37.49.152.140 and 2a04:d480:4400:11:200:5eff:fe00:1e3. No action of any kind should be required on customer side.

All previous IP addresses and ranges remain active. Customers of CH instance are not affected in any way.