Free tools
DNS A record lookup
Enter a hostname such as an MX target or SMTP server name.
What this checks
IPv4 addresses for the hostname, TTL, multiple A record round-robin, and resolution status.
Why it matters
Mail hosts must resolve correctly. A record mismatches between HELO hostname and connecting IP hurt reputation and FCrDNS alignment.
Results
Common issues
- HELO hostname resolves to a different IP than the connecting SMTP client.
- Multiple A records with round-robin where PTR only covers one IP.
- Stale A records after migrating mail infrastructure.
How to fix
- Align HELO, PTR, and forward A record to the same sending IP where possible.
- Update DNS after IP or hostname changes and wait for propagation.
- Document active sending IPs in MailFleet provider profiles.
How MailFleet helps
MailFleet SMTP diagnostics complement A record checks when validating provider hostnames before campaigns.
Related free tools
Delivery note: MailFleet helps users manage campaigns through their own sending providers. Delivery outcomes depend on sender reputation, DNS authentication, content quality, recipient engagement, list quality, provider rules, and mailbox filtering systems.
For regulatory context on commercial email in the United States, see the FTC CAN-SPAM compliance guide.
Frequently asked questions
For best practice, the sending IP should have PTR matching HELO, and HELO should forward-resolve to that IP (FCrDNS).
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