According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Masterbase is the email service provider (ESP) for 288 domains — 0.05% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Masterbase is an email service provider (ESP) that authenticates outbound mail for its customer base through SPF mechanisms, making it identifiable across the Tranco top-1 million websites. The platform's presence is strongest in Chile and distributed across multiple jurisdictions, positioning it as a provider for smaller to medium-sized senders rather than large-scale enterprise services.
For deliverability teams and sysadmins evaluating mail from Masterbase-authenticated sources, the key footprint insight is that this ESP is frequently paired with Microsoft 365 in the same organisations, indicating a pattern of hybrid email infrastructure. Understanding this topology is essential for reputation management and compliance practices, as the platform serves a diverse customer ecosystem sharing authentication infrastructure.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 6 | 2.1% |
| Top 100,000 | 68 | 23.6% |
| Top 1,000,000 | 203 | 70.5% |
| Unranked | 11 | 3.8% |
| TLD | Domains | Share | |
|---|---|---|---|
| .cl | 123 | 42.7% | |
| .com | 53 | 18.4% | |
| .pe | 22 | 7.6% | |
| .com.pe | 22 | 7.6% | |
| .com.co | 13 | 4.5% | |
| .co | 11 | 3.8% | |
| .ec | 9 | 3.1% | |
| .com.ec | 7 | 2.4% | |
| .com.mx | 6 | 2.1% | |
| .bo | 6 | 2.1% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 288 domains.
| Type | Service | Domains | Share of Masterbase users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 129 | 44.8% |
| Mailbox | Google Workspace | 61 | 21.2% |
| Mailbox | Self-Hosted | 23 | 8.0% |
| Mailbox | Unknown / Other | 19 | 6.6% |
| Mailbox | Trend Micro | 15 | 5.2% |
| Mailbox | Proofpoint | 11 | 3.8% |
| ESP | Amazon SES | 50 | 17.4% |
| ESP | Mandrill | 23 | 8.0% |
| ESP | emBlue | 22 | 7.6% |
| ESP | SendGrid (Twilio) | 21 | 7.3% |
Masterbase customers publish SPF records that designate the ESP's infrastructure as authorised to send on their behalf, making each domain's email reputation dependent on the aggregate behaviour of Masterbase's customer base. For deliverability practitioners, this means that filtering, rejection, or complaints flagged against one Masterbase sender can influence the overall reputation associated with the platform's IP space, affecting delivery for all Masterbase-authenticated mail. Organisations using Masterbase should monitor their sending reputation independently and maintain strict compliance with authentication and list hygiene standards to protect both their domain reputation and the broader platform's standing.
See the full Masterbase data page (KPI cards, trend, sample domains) →
Masterbase is a regional ESP primarily serving smaller to medium-sized senders, with strong presence in Chile and frequent pairing with Microsoft 365 in hybrid email setups. Testing against Masterbase is only necessary if you send through it or interact with Masterbase customers; otherwise, it is a lower priority than major cloud providers.
288 domains in the Tranco top-1M use Masterbase 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.
Masterbase 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.
Masterbase's largest TLD is .cl (42.7% of its domains); it appears across 17 TLDs in total.