Switching MX Records for 138 Enterprise Email: Key Checks and Maintenance Guide

Who this guide is for

This checklist is designed for IT administrators, compliance leads, and cross-border business teams managing 138 Enterprise Email. It focuses on the operational checks required when switching MX records to ensure uninterrupted email delivery, maintain security posture, and support multi-device access across web, mobile, PC, and standard protocol clients.

Why MX switching matters for enterprise email

MX records direct incoming mail to the correct mail servers. When transitioning to 138 Enterprise Email, changing MX records is a critical step that affects inbound routing, sender authentication alignment, and global delivery performance. A controlled switch minimizes the risk of lost messages, delayed replies, or compliance gaps during the transition period.

Pre-switch verification checklist

Before updating DNS, confirm the following:

• Domain control and DNS access: Ensure you have administrative access to the domain registrar or DNS hosting provider. 138 Enterprise Email requires a custom domain that you fully control.
• Current MX inventory: Document all existing MX records, including hostnames, priorities, and associated services. Save a backup configuration to enable a quick rollback if needed.
• 138-provided parameters: Obtain the exact MX hostnames, priorities, and any required verification records from the 138 Enterprise Email admin portal or official support channel. Do not use third-party or outdated values.
• Email source mapping: List all systems that send email on behalf of your domain, including CRM, ERP, marketing platforms, and notification services. These will need SPF/DKIM alignment after the MX switch.

Step-by-step MX transition process

1. Lower TTL in advance: Reduce the Time-to-Live (TTL) of your existing MX records to 300–600 seconds at least 24 hours before the change. This speeds up DNS propagation and reduces caching delays.
2. Add new MX records: Enter the 138 Enterprise Email MX records exactly as provided. Do not remove existing records until propagation is confirmed.
3. Monitor propagation: Use DNS lookup tools to verify that the new MX records are visible across multiple regions. Propagation can take up to 48 hours depending on your DNS provider and global caching.
4. Validate inbound routing: Send test emails from external accounts (including international domains) to confirm delivery to 138 mailboxes. Check spam folders and delivery logs if messages are delayed.
5. Remove old MX records: Once inbound routing is stable, delete legacy MX entries to prevent split delivery or routing loops.

Post-switch security and delivery checks

After MX records are active, verify the following to maintain email security and compliance:

• SPF alignment: Ensure your SPF record includes all authorized sending servers, including 138's outbound infrastructure. Avoid multiple conflicting SPF records.
• DKIM signing: Confirm that outbound emails are signed with the correct DKIM selector and that the public key matches the DNS record.
• DMARC policy: Start with a monitoring policy (`p=none`) to collect alignment reports. Gradually move to `p=quarantine` or `p=reject` once SPF and DKIM are fully aligned.
• Multi-device sync: Test access via webmail, mobile apps, PC clients, and third-party clients using standard SMTP/IMAP/POP protocols. Verify that sent items, folders, and attachments sync correctly.
• Global delivery: For cross-border teams, test sending and receiving with partners in key markets. 138 Enterprise Email supports global multi-node delivery, but regional DNS caching or local filtering may still affect timing.

Risk boundaries and rollback guidance

• Propagation delays: DNS changes are not instantaneous. During the transition window, some messages may route to old servers. Maintain a forwarding rule or temporary dual-MX setup if business continuity is critical.
• Authentication mismatches: Incorrect SPF/DKIM/DMARC configuration can cause legitimate emails to be marked as spam or rejected. Use 138's official verification tools and avoid manual record edits unless instructed.
• Rollback readiness: Keep a documented rollback plan that includes original MX values, TTL settings, and contact information for official support. If delivery anomalies persist beyond 48 hours, revert to the previous configuration and engage 138's direct-operated support team.

Next steps

• Review your current DNS configuration and prepare a change window with minimal business impact.
• Obtain the latest MX and authentication parameters from the 138 Enterprise Email admin console or official service portal.
• Schedule a test migration with a small user group before full deployment.
• For complex environments involving multiple domains, legacy systems, or strict compliance requirements, contact 138's official support for guided configuration and migration assistance.

Official direct-operated activation, migration, and operation and maintenance support are available through the 138 Enterprise Email service portal. All configuration parameters, service boundaries, and support terms are subject to the latest official documentation and contract specifications.