Servers in multiple geographic zones

DuoCircle filters mail in two regions: the United States and the European Union. Our global MX records balance your mail across both regions. If one region has a connectivity problem, the other keeps accepting your mail.

Some customers must keep their mail inside one region. We support this. Choose the set of MX records below that matches your requirement.

Every set uses the same four hostnames. Email Backup MX differs in one way only: your own mail server takes priority 10, and our records take the higher priority numbers.

Global filtering — both regions

This is the right choice for most customers. We filter your mail in whichever region is healthy and closest at the time.

Email Gateway and Email Forwarding:

MX 10  your custom MX record (from the portal) or mx1.mailhop.org
MX 20  mx1.mailhop.us
MX 30  mx1.mailhop.co
MX 40  mx1.mailhop.co.uk

Email Backup MX:

MX 10  mail.yourdomain.com
MX 20  your custom MX record (from the portal) or mx1.mailhop.org
MX 30  mx1.mailhop.us
MX 40  mx1.mailhop.co
MX 50  mx1.mailhop.co.uk

European Union only

These records keep your mail inside the European Union. We filter it in Frankfurt, Germany.

Email Gateway and Email Forwarding:

MX 10  mx1.eu.mailhop.org
MX 20  mx1.eu.mailhop.us
MX 30  mx1.eu.mailhop.co
MX 40  mx1.eu.mailhop.co.uk

Email Backup MX:

MX 10  mail.yourdomain.com
MX 20  mx1.eu.mailhop.org
MX 30  mx1.eu.mailhop.us
MX 40  mx1.eu.mailhop.co
MX 50  mx1.eu.mailhop.co.uk

United States only

These records keep your mail inside the United States.

Email Gateway and Email Forwarding:

MX 10  mx1.us.mailhop.org
MX 20  mx1.us.mailhop.us
MX 30  mx1.us.mailhop.co
MX 40  mx1.us.mailhop.co.uk

Email Backup MX:

MX 10  mail.yourdomain.com
MX 20  mx1.us.mailhop.org
MX 30  mx1.us.mailhop.us
MX 40  mx1.us.mailhop.co
MX 50  mx1.us.mailhop.co.uk

Notes on these records

  • Add all four DuoCircle records in a set. They use four top-level domains held at two different DNS providers. If one DNS provider or one registry fails, senders can still resolve one of the others. See MX Records with Redundant DNS Providers.
  • Names such as mx1.eu.mailhop.us and mx1.us.mailhop.co.uk look contradictory. The country in the top-level domain has no meaning here. The region is the label directly after mx1. — either us or eu.
  • A custom MX record from the portal (a######.mx.mailhop.org) is global. If you need single-region filtering, use the regional records instead.
  • Older setups use mx2. or mx3. hostnames. Those records still work, so your mail keeps flowing. Move to the mx1. records above when it is convenient. Only the mx1. names have regional equivalents, so an mx2. setup cannot use single-region filtering.

Updating your firewall

If a firewall sits in front of your mail server, allow the addresses we deliver from. The set you need depends on the MX records you chose:

  • Global MX records — allow both the United States set and the European Union set.
  • mx1.eu. records only — allow the European Union set.
  • mx1.us. records only — allow the United States set.

If you choose a single region, we keep your mail in that region. We do not move it to the other region, so you do not need to allow the other region's addresses.

The current address lists are here: IP Addresses for Firewalls.

If you deliver to Google Workspace or Microsoft 365, a firewall rule is not enough. Those platforms keep a separate list of trusted inbound sources. The firewall article links to the setup steps for both.

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