Useful during SMTP outages
Temporary queuing can help during connectivity failures, maintenance and an unreachable primary mail server.
SECURAWALL MAILFLOW
Backup MX Service: Secondary Mail Exchanger
UNDERSTAND THE SERVICE
Backup mail exchanger, secondary MX or Cloud Backup MX?
These terms describe an additional inbound SMTP route for your domain. SecuraWall keeps eligible accepted messages in a temporary queue and retries your existing receiving destination. Your mailboxes remain with your current provider.
Choose Cloud Backup MX
Evaluate routing, queue limits and destination requirements before adding a secondary mail exchanger.
Read the guide →Cloud email gateway protection
Explore the incoming spam and malware checks available with Email Protection, and understand their limits.
Review protection scope →Cloud Backup MX without moving your mailboxes
A backup mail exchanger, also called a secondary MX, provides an additional inbound SMTP route for an existing domain. SecuraWall runs this route in the cloud and temporarily queues eligible accepted messages when your configured destination cannot receive them.
A secondary route for accepted incoming email
When a sender uses your secondary MX, SecuraWall can accept eligible messages and retry delivery to your existing destination. Senders choose which MX to contact; publishing a backup record does not force every message through us or guarantee that a sender will retry after a permanent rejection.
Keep your existing mailboxes
Your current provider remains responsible for recipient validation, mailbox storage, policies and final inbox placement.
Know the scope
Backup MX is not full email continuity: there are no hosted mailboxes, webmail, outbound email access or guaranteed message recovery while your primary service is down.
One Backup MX plan for each domain
Backup MX uses a secondary route and queues/forwards without mailbox pre-checks or content scanning. Email Protection uses the only published MX and adds spam, antivirus and quarantine. Choose optional SMTP Relay for authenticated outgoing SMTP with either base package. Select one base package per domain.
Confirm that your primary provider accepts forwarded SMTP mail from the gateway. Cloud mail providers may require connector or policy configuration; compatibility is not automatic.
Explore packages and add-ons
Related technical guidance
Queue, capacity and deletion conditions
Current plan: up to 14 days in the delivery queue; retries approximately every 3 minutes; maximum complete encoded message 50 MiB (52,428,800 bytes). Attachments grow when encoded. A domain may have a lower message limit.
No per-message charge or advertised message-count cap. Storage is finite and shared: there is no unlimited disk allocation or reserved per-domain capacity. Acceptance remains subject to available resources, active service and configured security policies.
A destination SMTP acceptance removes the message from the delivery queue; it does not prove delivery to an inbox. Temporary 4xx failures are retried within the remaining lifetime. Permanent 5xx failures normally end that delivery attempt with a failure notification. These notifications can themselves fail.
Undelivered mail expires after the configured lifetime, including time spent paused. Quarantined mail is removed at its retention deadline. Confirmed domain deletion permanently purges queued and held messages. If a queued message has recipients in multiple domains, deleting it removes it for every pending recipient. Delivered, expired or deleted messages are not a customer archive.
Ready to configure your domain?
Review the setup and conditions before purchasing.
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