Cisco Secure Email (IronPort) and Talos Reputation Blocks

When a company running Cisco Secure Email (the product long known as IronPort) rejects your mail for "poor reputation," its gateway has looked up your sending IP in Cisco Talos's reputation data and decided your score is too low. Look up your IP on Talos, fix whatever is dragging it down, and give it three to five days to recover. If it doesn't, open a Sender IP Reputation dispute with Talos. If your IP is rated fine, the block is that recipient's own policy, and their admin has to change it.

Cisco's gateways protect a lot of corporate, government and university mail, so a Talos problem tends to show up as bounces from many unrelated business domains at once.

What a Cisco reputation block looks like

Cisco's own TechNote shows the standard rejection a gateway sends when your reputation score falls in its blocked range:

554 Your access to this mail system has been rejected due to the sending
MTA's poor reputation. If you believe that this failure is in error, please
contact the intended recipient via alternate means.

Recipients can customize this text, so you'll also see shorter variants. Two clues that you're dealing with Cisco: the phrase "poor reputation," and an MX hostname ending in iphmx.com, which is the domain Cisco's cloud gateway uses for customer MX records (for example mx1.hc1234-56.iphmx.com). You can check the recipient domain's MX records to confirm.

How Talos reputation works

Talos is Cisco's threat intelligence group. It publishes a reputation for IP addresses and domains based on what Cisco's network sees across its customers. The public face of it is the Talos Reputation Center, where you can look up any IP.

Talos shows three levels:

Behind those labels is a numeric score from -10 (worst) to +10 (best), historically called the SenderBase Reputation Score (SBRS). Each recipient's gateway decides what to do with it. Cisco says the common setup throttles senders with no score or slightly negative scores and blocks more negative ones, but every installation sets its own ranges. A sample log line in Cisco's documentation shows a block group matching scores from -10 to -3.

Two things follow from that:

• Talos doesn't block your mail. Its customers do. Talos says as much: it publishes the reputation, and each organization's gateway acts on it.
• "Neutral" can still get you blocked at a recipient with strict settings. A score of None (not enough data) is common for low-volume or brand-new IPs and is often throttled.

The common causes, most likely first

Talos lists three main reasons for a Poor rating, and they line up with what usually turns up in practice:

1. Spam reports and blocklist listings. If your IP is on common DNS blocklists, Talos will know. The Reputation Center has a DNS-based blocklist section that shows them. Check Spamhaus, SpamCop and Barracuda first.
2. DNS patterns that look like a compromised machine. Talos points to RFC 5321's rules for the HELO/EHLO name. Missing or generic reverse DNS, or a HELO that says "localhost," looks like a botnet.
3. Links to malicious domains. Mail that links to domains hosting or distributing malware drags the sending IP down, even if the sender didn't mean any harm. Compromised WordPress sites in your links count.
4. A shared IP. If you send through an ESP or hosting provider, other customers' traffic affects the score. See My ESP's shared IP is blacklisted.
5. A new or low-volume IP with no history. That's a None or Neutral score, not a Poor one, and the fix is a gradual, consistent ramp.

How to fix it, step by step

1. Get the IP from the bounce. If you send through Microsoft 365, Google Workspace or an ESP, the IP belongs to them.
2. Look it up in the Talos Reputation Center at talosintelligence.com. Note the email reputation level and any blocklist listings shown.
3. Clear any public blocklist listings first. They feed into Talos, so a lingering Spamhaus listing will keep your score down no matter what you tell Talos.
4. Fix the basics on any server you run: a PTR record that resolves to a real hostname, which resolves back to the same IP, and a HELO name that matches. Make sure SPF, DKIM and DMARC pass; the email authentication checker covers the DNS side.
5. Find and stop the bad traffic. Check outbound logs for compromised accounts, abused web forms and malware. If you send marketing mail, look at where recent addresses came from and cut anything unengaged or purchased.
6. Check the links in your mail. Every domain you link to, including tracking domains, should be clean.
7. Wait three to five days. Talos says that once the problem is fixed, the score should improve on its own in that window.
8. If it doesn't, file a dispute. On TalosIntelligence.com, choose a Sender IP Reputation ticket (or Sender Domain Reputation if a domain is the issue), enter the IP, choose "Not Malicious" and explain what was wrong and what you changed. Talos says repeated tickets for the same IP won't speed anything up, so file once and file well.
9. If your IP is rated Good or Neutral and one company still rejects you, it's their policy. Ask your contact to have their IT team check the gateway logs and add your IP to an allowed sender group. Cisco documents exactly how admins do this.

How to confirm it's fixed

Recheck the IP on Talos until the email reputation reads Good or at least Neutral. Then resend to a recipient that bounced, and watch your logs for 554 "poor reputation" responses from iphmx.com and other Cisco-protected hosts over the next week.

How to keep it from coming back

• Keep reverse DNS, HELO and authentication correct whenever you change servers or providers.
• Watch the major public blocklists and act on a listing the same day.
• Enforce multi-factor authentication and outbound rate limits so a phished account can't turn your IP into a spam source.
• Ramp new IPs gradually and keep volume steady; a long gap followed by a big blast looks suspicious to every reputation system.
• Keep lists clean and engaged. The causes in Why are my emails going to spam? apply here too.

For the other enterprise gateways you'll run into, see Proofpoint, Mimecast and Barracuda.

When to get help

If your Talos score stays Poor after you've cleaned up, or you can't find what's sending from your IP, it's worth having someone go through your logs and sending setup with you. Get in touch.

FAQ

Is Talos a blacklist?

Not in the classic sense. Talos publishes reputation scores that Cisco's gateways use, and each recipient decides what score to block. It does show public blocklist listings in its lookup, but those come from other lists.

How long does it take for a Talos reputation to improve?

Talos says it should improve automatically within three to five days once the cause is fixed. If it doesn't, file a dispute.

Can I pay Cisco or Talos to fix my reputation?

No. There's no paid removal. Fix the cause, let the score recover, and use the free dispute process if it doesn't.

Why is only one Cisco customer blocking me?

Each Cisco customer sets its own thresholds and allow or block lists. If your Talos rating is fine elsewhere, that recipient's settings are stricter, and only their admin can adjust them.