Companies Using Cisco Email Security

I'm Mehmet Suleyman, CEO and co-founder of TechnologyChecker.io. Before this I worked at Microsoft, on Bing search and then its AI team, where I got hands-on with web crawling infrastructure. This analysis covers 11,136 domains routing mail through Cisco Email Security as of our September 2026 crawl, 8,275 of them matched to a company record, a 74.3% enrichment rate. Of everything we publish, this is the mechanism I trust most. The rule is one MX record pointing at Cisco's iphmx.com hosts: live inbound mail routing, not a badge or a DNS token. A detection means mail is flowing through Cisco right now and stops matching the day the customer repoints MX. On a random 400-domain re-check, 393 still routed to Cisco, 98.3%.

Growth trajectory

Four monthly points, 9,229 in June to 11,136 in September, and most of that rise is us rather than Cisco. Of the 4,329 current domains first detected in June, 4,229 were reached by our crawl within three days. July says the same at 1,241 of 1,364. September is the exception: only 45 of its 104 new detections sat on a domain new to us. Read the line as a trend, not a same-domain comparison, because the crawled set turns over every month, dead sites out and newly found ones in, and our detection widens as it goes. The signal itself doesn't flicker: across active rows, average detections equals average scans exactly, 5.04 against 5.04.

Sales Signal: 647 domains have dropped Cisco since we began tracking it in March 2026, 5.8% of the live base. This signal can't flicker, so every one really changed provider.

"Most technology detection is inference. This one isn't. A domain either points its mail at Cisco or it doesn't, and when it stops we know the same week." - Mehmet Suleyman, CEO & Co-founder at TechnologyChecker.io

Customer profile

1,365 of the 7,976 companies with a size on record employ more than 1,000 people, 17.11%, and the age chart agrees: Pre-1960 is the largest founding band at 23.08%, and 38.53% of the 5,048 companies with a founding year predate 1980. Deloitte, Capgemini, Starbucks, Allianz and Santander are all here on head-office domains, not campaign microsites, because a microsite rarely publishes its own mail routing. The 1-10 band is still the largest bucket at 24.13%, and that needs the unit explained. Cisco writes a per-customer allocation into the MX hostname, so we grouped a sample by it: 323 domains resolve to 228 distinct accounts, 1.42 domains per account, the largest holding 21, and 42.7% sit in a multi-domain account.

Sales Signal: treat this as 1.4 domains per buying centre and dedupe by MX allocation first, or you'll call one procurement team three times.

Industry and geographic concentration

Financial Services leads at 8.38% of the 7,542 companies with an industry, and the regulated block, financial services plus healthcare, insurance, banking and government administration, comes to 1,622 companies, 21.51%, and no other single industry reaches 5%. This is less American than most enterprise software we track: the US is 3,285 of 8,107 matched companies, 40.52%, while the eight European countries in our top fifteen add to 2,170, 26.77%. Germany is second at 523, with Spain (355) and France (298) both ahead of the UK (289).

Sales Signal: Germany, Spain and France hold 1,176 matched companies between them, more than a third of the US total, and they are the least contested end of this list.

Migration patterns

Mail routing is exclusive, so every row in the migration table is a replacement. 443 domains moved from Cisco to Microsoft 365, 145 in the last 30 days, against 84 to Proofpoint. Both clear the test we apply before publishing a corridor: of the 636 that left Cisco entirely, 69.65% now route to Microsoft against 5.15% of those that stayed, a 13.5x lift on a 5.3:1 direction ratio, while Proofpoint reads 13.21% of leavers against 0.41% of stayers, 32x on 84:1. No burst, no single customer: the largest single day is 40 of the 443. Microsoft also returns 84 domains, with Google Workspace sending 22. Our Mimecast page found the same shape from a different base.

Sales Signal: two lists, two pitches. The 443 on Microsoft are a layered-defence audience; the 84 on Proofpoint prove a standalone gateway still wins here.

"Cisco loses more than five times as many domains to Microsoft as to Proofpoint. A mail gateway's real competitor stopped being another gateway a while ago; it's the mailbox provider bundling good enough into the licence." - Mehmet Suleyman, CEO & Co-founder at TechnologyChecker.io

Technology ecosystem

One line needs explaining before anyone quotes it. Microsoft 365 appears on 5.15% of the 11,126 live domains, and both rules read the MX record, so on paper they should be mutually exclusive. They aren't: a domain can publish several mail hosts at different preferences. We checked six live and every one had Cisco at the lowest preference with Outlook behind it, nicoletcollege.edu publishing Cisco at 10 and Outlook at 100. That is Cisco filtering in front of Microsoft mailboxes, and 5.15% is a floor, because most gateway customers hand mail to Microsoft privately with no public Outlook MX.

The rest of the table is the web, not the mail path: WordPress on 32.84% and Cloudflare on 33.03%. One figure we cut before publishing: Apple iCloud Mail would have read 15.7% here, because its rule ORs MX with a TXT apple-domain token, and on four of four sampled domains that token was a stale verification string while mail went to Cisco.

Sales Signal: the 573 domains publishing both Cisco and Microsoft mail hosts already pay twice for mail security, so a consolidation pitch lands on an existing budget.

What the data cannot tell you

Three limits. We see the gateway, not the mailbox behind it: unless a domain also publishes its platform's MX, we can't tell whether Cisco is filtering for Exchange, Microsoft 365 or something else, which is why 5.15% is a floor. Cisco Secure Email Threat Defense is a different, API-based product that sits inside the mailbox rather than the MX path, and we don't measure it. And the count is domains, not customers: at 1.42 per account, 11,136 domains is closer to 7,800 buying relationships. On reviews, G2's gateway listing, Cisco IronPort, averages 4.3 out of 5 from 22 reviews, too thin for a pros and cons table.

Key takeaways

1. The mechanism is the story. One MX clause, 393 of 400 sampled domains still routing to Cisco, detections equal to scans.

2. Mid-market and enterprise. 17.11% employ more than 1,000 people; 38.53% predate 1980.

3. The unit is the account. 1.42 domains per account, 42.7% inside a multi-domain contract.

4. The pressure comes from Microsoft. 443 domains out to Microsoft 365 against 84 to Proofpoint, a 13.5x lift.

5. The number is a floor twice over. The 5.15% overlap understates the gateway-in-front pattern; Threat Defense leaves no trace.

Sales applications

Outreach angle: "Your MX points at Cisco's iphmx.com hosts, so inbound mail runs through the Secure Email Gateway. We've watched 443 domains move off it to Microsoft 365 and 84 to Proofpoint. Worth twenty minutes on where yours is heading?" Targeting: on TechnologyChecker.io, filter to 1,000+ employees in financial services, insurance and healthcare, then intersect with the 573 that also publish a Microsoft 365 mail host. Competitive angle: the 145 that left for Microsoft in the last 30 days have just reopened a budget.

Every figure above comes from our crawl and enrichment: 11,136 domains routing mail through Cisco Email Security and 8,275 enriched companies. Filter them by size, country and industry, or set them against Mimecast and the rest of the Email Security category.