IS.CC Relay email provider statistics and deliverability context
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According to Live Direct Marketing's daily Tranco top-1M scan (September 10, 2026), IS.CC Relay is the email service provider (ESP) for 103 domains — 0.02% of 632,322 SPF-publishing domains. Its strongest TLD is .com (57.3% of its domains). Detection: include: mechanisms in the SPF record.
Last updated from the 2026-09-10 DNS snapshot.
What IS.CC Relay represents in this dataset
IS.CC — generic SMTP relay service.
Directory category: Gateway. The classification comes from include: mechanisms in the SPF record. It describes observed DNS infrastructure, not a commercial relationship and not the placement of any individual message.
What the 2026-09-10 snapshot shows about IS.CC Relay
Across 25 distinct TLDs its top three are .com (57.3%), .org (9.7%), .net (6.8%) — together 73.8% of the 103 domains, which makes the footprint narrow — three TLDs cover most of it, which is typical of a regional or single-market operator. The service most often observed on the same domains is Self-Hosted (Mailbox, 87 domains, 84.5% of them), followed by Google Workspace (7.8%). Directly comparable by the same detection rule: Amazon SES, SendGrid (Twilio), Mailgun. Ranking between them reflects what is published in DNS, not delivery quality or volume sent. All figures come from a single daily DNS snapshot (2026-09-10); a domain appears here when its published records match the include: mechanisms in the SPF record rule, which is an infrastructure fact, not a commercial relationship.
Commonly used together with IS.CC Relay
What else the same 103 domains use — cross-tabulated from the same daily snapshot (2026-09-10).
| Type | Service | Domains | Share of IS.CC Relay users |
|---|---|---|---|
| Mailbox | Self-Hosted | 87 | 84.5% |
| Mailbox | Google Workspace | 8 | 7.8% |
| Mailbox | Generic / unmatched (mx*.*) | 2 | 1.9% |
| Mailbox | Microsoft 365 | 2 | 1.9% |
| Mailbox | Unknown / Other | 2 | 1.9% |
| Mailbox | Barracuda | 1 | 1.0% |
| ESP | MailChannels | 26 | 25.2% |
| ESP | Amazon SES | 3 | 2.9% |
| ESP | SpamExperts (AntiSpamCloud) | 1 | 1.0% |
| ESP | Zoho Campaigns | 1 | 1.0% |
TLD distribution (top 25 of 25)
Frequently asked questions
How many domains use IS.CC Relay?
103 domains in the Tranco top-1M use IS.CC Relay as their email service provider (ESP) as of September 10, 2026, according to Live Direct Marketing's daily DNS scan.
What is IS.CC Relay's market share?
IS.CC Relay holds 0.02% of SPF-publishing domains in the Tranco top-1M (snapshot of 2026-09-10). The number is recomputed every day.
What are the biggest alternatives to IS.CC Relay?
The largest email service provider (ESP)s in the same category by Tranco top-1M share are: Amazon SES, SendGrid (Twilio), Mailgun, Zendesk, Mailchimp (as of 2026-09-10).
Largest email service provider (ESP)s in this category
Amazon SES (6.15%) · SendGrid (Twilio) (4.62%) · Mailgun (4.00%) · Zendesk (3.75%) · Mailchimp (3.56%) · Mandrill (3.24%) · HubSpot (3.09%) · Salesforce (2.54%) · Mailjet (Sinch) (2.11%) · Cloudflare Email Routing (1.93%)
Domain sample (top 100 by Tranco rank)
Showing 100 of 103 domains.