Send-Box email service provider (ESP)

According to Live Direct Marketing's daily Tranco top-1M scan (July 12, 2026), Send-Box is the email service provider (ESP) for 119 domains — 0.02% of 617,244 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.

Key facts

Send-Box is a Russian-focused email service provider that operates primarily in the .ru market, serving smaller organisations and regional deployments. It is most commonly encountered as part of email infrastructure in Russian and Eastern European markets, often appearing alongside Mail.ru for Business within the broader regional email ecosystem.

For senders and mail infrastructure operators, Send-Box's concentrated footprint in regional markets means it rarely poses the high-volume sender reputation challenges of mainstream global providers. However, when targeting or receiving mail involving Russian or Eastern European users, understanding Send-Box's presence in SPF records and routing paths becomes relevant to sender authentication validation and infrastructure planning.

Where Send-Box sits in the Tranco ranking

Tranco rank bandDomainsShare of its base
Top 1,00000.0%
Top 10,00010.8%
Top 100,0002016.8%
Top 1,000,0009075.6%
Unranked86.7%

Top-level domain split

TLDDomainsShare
.ru8773.1%
.com119.2%
.kz86.7%
.net21.7%
.site10.8%
.fm10.8%
.info10.8%
.online10.8%
.by10.8%
.pro10.8%

What Send-Box users also use

Cross-tabulated from the same daily snapshot — the other email services seen on the same 119 domains.

TypeServiceDomainsShare of Send-Box users
MailboxMail.ru for Business4437.0%
MailboxSelf-Hosted2722.7%
MailboxYandex 3602621.8%
MailboxGoogle Workspace75.9%
MailboxUnknown / Other43.4%
MailboxGeneric / unmatched (mx*.*)32.5%
ESPUnisender (RU)3428.6%
ESPSMTP.BZ1512.6%
ESPSendPulse1310.9%
ESPDashaMail (RU)97.6%

SPF Include Chains and Authentication Path Complexity

Send-Box appears in detection datasets primarily through SPF include mechanisms, indicating it serves as a delegated mail routing component for its users. When an organisation includes Send-Box in their SPF record alongside other regional providers, each include requires DNS lookups during mail server authentication checks. This multi-provider stacking, particularly common in Eastern European deployments, means DMARC and SPF validators must account for multiple possible sender pathways and handle authentication results from several routing layers.

See the full Send-Box data page (KPI cards, trend, sample domains) →

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Frequently asked questions

What is Send-Box and why does it appear in SPF records?

Send-Box is a Russian-focused email service provider that appears as an SPF include for regional organisations. It is primarily concentrated in smaller-scale deployments in the .ru market rather than global enterprise infrastructure.

How many domains use Send-Box?

119 domains in the Tranco top-1M use Send-Box as their email service provider (ESP) as of July 12, 2026 (0.02% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.

Is Send-Box common enough to affect email deliverability testing?

Send-Box accounts for 0.02% 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 Send-Box most?

Send-Box's largest TLD is .ru (73.1% of its domains); it appears across 15 TLDs in total.

Other email service provider (ESP)s

Amazon SES (6.21%)SendGrid (Twilio) (4.75%)Mailgun (4.11%)Zendesk (3.87%)Mailchimp (3.69%)Mandrill (3.36%)HubSpot (3.18%)Salesforce (2.62%)Mailjet (Sinch) (2.13%)Cloudflare Email Routing (1.80%)