According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Cisco IronPort (ICPbounce) is the email service provider (ESP) for 317 domains — 0.05% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Cisco IronPort (marketed as ICPbounce) is an email delivery and security platform operated by Cisco Systems that enables organizations to send bulk email, manage sender reputation, and filter abuse across their outbound mail infrastructure.
IronPort's footprint skews towards smaller and mid-market sites rather than the largest brands, concentrated in .com registrations, and most often appears alongside Microsoft 365. For email professionals, this pattern signals that multi-sender orchestration—especially in Microsoft-integrated environments—is common, requiring careful SPF alignment and reputation monitoring across parallel sending channels.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 1 | 0.3% |
| Top 10,000 | 2 | 0.6% |
| Top 100,000 | 28 | 8.8% |
| Top 1,000,000 | 264 | 83.3% |
| Unranked | 22 | 6.9% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 203 | 64.0% | |
| .org | 53 | 16.7% | |
| .net | 10 | 3.2% | |
| .edu | 10 | 3.2% | |
| .co.uk | 6 | 1.9% | |
| .gov | 4 | 1.3% | |
| .ca | 3 | 0.9% | |
| .co.nz | 3 | 0.9% | |
| .be | 2 | 0.6% | |
| .nl | 2 | 0.6% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 317 domains.
| Type | Service | Domains | Share of Cisco IronPort (ICPbounce) users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 103 | 32.5% |
| Mailbox | Google Workspace | 84 | 26.5% |
| Mailbox | Proofpoint | 25 | 7.9% |
| Mailbox | Mimecast | 22 | 6.9% |
| Mailbox | Unknown / Other | 20 | 6.3% |
| Mailbox | Self-Hosted | 13 | 4.1% |
| ESP | Amazon SES | 44 | 13.9% |
| ESP | SendGrid (Twilio) | 41 | 12.9% |
| ESP | Mailchimp | 25 | 7.9% |
| ESP | HubSpot | 24 | 7.6% |
When IronPort SPF includes appear on a domain—particularly those already using Microsoft 365—they typically indicate a secondary or specialized sending path rather than the primary outbound route. This split-sender architecture can introduce reputation fragmentation if the domains are not properly coordinated through authentication records (SPF, DKIM, DMARC), and monitoring both sending channels' bounce and complaint rates becomes essential for maintaining consistent deliverability.
See the full Cisco IronPort (ICPbounce) data page (KPI cards, trend, sample domains) →
Your domain's SPF record includes a reference to Cisco IronPort's infrastructure if you use their email delivery service or a third-party application that sends mail on your behalf using IronPort. This is normal if IronPort is one of your authorized sending channels.
317 domains in the Tranco top-1M use Cisco IronPort (ICPbounce) as their email service provider (ESP) as of July 13, 2026 (0.05% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Cisco IronPort (ICPbounce) accounts for 0.05% of SPF-publishing domains in the top 1M. Whether you should seed a test mailbox there depends on how much of your audience it represents — the co-usage table above shows the services it appears alongside most.
Cisco IronPort (ICPbounce)'s largest TLD is .com (64.0% of its domains); it appears across 31 TLDs in total.