Masterbase email service provider (ESP)
According to Live Direct Marketing's daily Tranco top-1M scan (September 22, 2026), Masterbase is the email service provider (ESP) for 292 domains — 0.05% of 637,585 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Key facts
- 292 domains in the Tranco top-1M use Masterbase (0.05% of SPF-publishing domains).
- Snapshot date: 2026-09-22 — recomputed every day.
- Strongest TLD: .cl (42.1% of its domains).
- Most co-used service: Microsoft 365.
- Directory category: email service provider.
Why Masterbase appears in this category
Chilean marketing automation, LatAm reach.
We classify it as a email service provider from include: mechanisms in the SPF record matching a maintained provider rule. This is infrastructure attribution from public DNS, not evidence of a direct contract or exclusive use.
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.
Where Masterbase sits in the Tranco ranking
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 6 | 2.1% |
| Top 100,000 | 69 | 23.6% |
| Top 1,000,000 | 216 | 74.0% |
| Unranked | 1 | 0.3% |
Top-level domain split
| TLD | Domains | Share | |
|---|---|---|---|
| .cl | 123 | 42.1% | |
| .com | 55 | 18.8% | |
| .pe | 22 | 7.5% | |
| .com.pe | 20 | 6.8% | |
| .co | 14 | 4.8% | |
| .com.co | 13 | 4.5% | |
| .ec | 10 | 3.4% | |
| .com.ec | 7 | 2.4% | |
| .bo | 6 | 2.1% | |
| .com.mx | 5 | 1.7% |
What Masterbase users also use
Cross-tabulated from the same daily snapshot — the other email services seen on the same 292 domains.
| Type | Service | Domains | Share of Masterbase users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 131 | 44.9% |
| Mailbox | Google Workspace | 63 | 21.6% |
| Mailbox | Self-Hosted | 21 | 7.2% |
| Mailbox | Unknown / Other | 19 | 6.5% |
| Mailbox | Trend Micro | 15 | 5.1% |
| Mailbox | Proofpoint | 12 | 4.1% |
| ESP | Amazon SES | 52 | 17.8% |
| ESP | Mandrill | 24 | 8.2% |
| ESP | emBlue | 24 | 8.2% |
| ESP | SendGrid (Twilio) | 22 | 7.5% |
SPF-authenticated sending and shared infrastructure reputation
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) →
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Frequently asked questions
What is Masterbase and is it important for email deliverability?
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.
How many domains use Masterbase?
292 domains in the Tranco top-1M use Masterbase as their email service provider (ESP) as of September 22, 2026 (0.05% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Is Masterbase common enough to affect email deliverability testing?
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.
Which countries or TLDs use Masterbase most?
Masterbase's largest TLD is .cl (42.1% of its domains); it appears across 18 TLDs in total.