FSI Email Security email provider statistics and deliverability context
← Email Stats homeesp
According to Live Direct Marketing's daily Tranco top-1M scan (September 11, 2026), FSI Email Security is the email service provider (ESP) for 603 domains — 0.10% of 631,089 SPF-publishing domains. Its strongest TLD is .jp (33.8% of its domains). Detection: include: mechanisms in the SPF record.
Last updated from the 2026-09-11 DNS snapshot.
What FSI Email Security represents in this dataset
FSI — Japanese managed email security.
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 2026-09-11 snapshot shows about FSI Email Security
Across 18 distinct TLDs its top three are .jp (33.8%), .com (29.2%), .co.jp (24.7%) — together 87.7% of the 603 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 FSI (JP ISP) (Mailbox, 256 domains, 42.5% of them), followed by Self-Hosted (14.3%). 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 (2026-09-11); 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 FSI Email Security
What else the same 603 domains use — cross-tabulated from the same daily snapshot (2026-09-11).
| Type | Service | Domains | Share of FSI Email Security users |
|---|---|---|---|
| Mailbox | FSI (JP ISP) | 256 | 42.5% |
| Mailbox | Self-Hosted | 86 | 14.3% |
| Mailbox | Google Workspace | 76 | 12.6% |
| Mailbox | Microsoft 365 | 57 | 9.5% |
| Mailbox | Unknown / Other | 49 | 8.1% |
| Mailbox | Kagoya (JP) | 13 | 2.2% |
| ESP | Q-Send | 177 | 29.4% |
| ESP | Amazon SES | 51 | 8.5% |
| ESP | Repica WebCAS | 43 | 7.1% |
| ESP | BizMatrix | 26 | 4.3% |
TLD distribution (top 18 of 18)
Frequently asked questions
How many domains use FSI Email Security?
603 domains in the Tranco top-1M use FSI Email Security as their email service provider (ESP) as of September 11, 2026, according to Live Direct Marketing's daily DNS scan.
What is FSI Email Security's market share?
FSI Email Security holds 0.10% of SPF-publishing domains in the Tranco top-1M (snapshot of 2026-09-11). The number is recomputed every day.
What are the biggest alternatives to FSI Email Security?
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 2026-09-11).
Largest email service provider (ESP)s in this category
Amazon SES (6.17%) · SendGrid (Twilio) (4.63%) · Mailgun (4.00%) · Zendesk (3.76%) · Mailchimp (3.56%) · Mandrill (3.24%) · HubSpot (3.10%) · Salesforce (2.54%) · Mailjet (Sinch) (2.12%) · Cloudflare Email Routing (1.93%)
Domain sample (top 100 by Tranco rank)
Showing 100 of 603 domains.