Which IP addresses does Rublon MFA send emails from?

Rublon MFA sends emails using Mailgun for Europe and Postmark for all other countries.

Europe

For this purpose, Europe includes 42 countries: EEA countries, Switzerland, the United Kingdom, the Balkans, Ukraine, Moldova, Turkey, and Georgia.

Mailgun dynamically manages the shared IP pool. The best source is SPF records.

The current list can be checked with a DNS query:

dig TXT _spf.mailgun.org

dig TXT _spf.eu.mailgun.org  # for EU region

To ensure that emails from Rublon MFA will not be marked as spam, add all of these IP addresses to your safe sender list in Office 365 or your email allowlist in Google Workspace.

Non-Europe

Rublon MFA sends emails from one of the Outbound SMTP Servers.

Each of the SMTP servers has its own IP range. There is no way to tell which of the IP addresses will be used to send you an email message.

To ensure that emails from Rublon MFA will not be marked as spam, add all of these IP addresses to your safe sender list in Office 365 or your email allowlist in Google Workspace.

Helpful Links

Mailgun - SPF records

Postmark - Outbound SMTP Servers

Create safe sender lists in EOP

Add IP addresses to allowlists in Gmail