Barracuda Email Security email service provider (ESP)
According to Live Direct Marketing's daily Tranco top-1M scan (September 12, 2026), Barracuda Email Security is the email service provider (ESP) for 344 domains — 0.05% of 629,828 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Key facts
- 344 domains in the Tranco top-1M use Barracuda Email Security (0.05% of SPF-publishing domains).
- Snapshot date: 2026-09-12 — recomputed every day.
- Strongest TLD: .com (34.0% of its domains).
- Most co-used service: Barracuda.
- Directory category: email security gateway.
Why Barracuda Email Security appears in this category
Barracuda Email Security Service (UK PoP).
We classify it as a email security gateway 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.
Barracuda Email Security is a cloud-based email filtering and protection service operated by Barracuda Networks, a security software company. It sits in the email infrastructure ecosystem as a gateway solution for organizations seeking to defend against phishing, spam, malware, and data loss — typically deployed by businesses of all sizes, but particularly common among mid-market and smaller organizations.
When you encounter Barracuda Email Security's SPF include mechanisms across the web, you are looking at a distributed presence across smaller and mid-market sites rather than the largest enterprise brands, spread globally across many top-level domains with .com leading. For senders and receivers, this means you are likely to encounter Barracuda's infrastructure when emailing smaller organizations or those without in-house email ops teams — it is a common choice for firms that outsource their security posture rather than build it in-house.
Where Barracuda Email Security sits in the Tranco ranking
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 0 | 0.0% |
| Top 100,000 | 28 | 8.1% |
| Top 1,000,000 | 311 | 90.4% |
| Unranked | 5 | 1.5% |
Top-level domain split
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 117 | 34.0% | |
| .co.uk | 104 | 30.2% | |
| .org.uk | 26 | 7.6% | |
| .org | 21 | 6.1% | |
| .ac.uk | 15 | 4.4% | |
| .gov.uk | 9 | 2.6% | |
| .net | 9 | 2.6% | |
| .ie | 6 | 1.7% | |
| .be | 3 | 0.9% | |
| .com.au | 3 | 0.9% |
What Barracuda Email Security users also use
Cross-tabulated from the same daily snapshot — the other email services seen on the same 344 domains.
| Type | Service | Domains | Share of Barracuda Email Security users |
|---|---|---|---|
| Mailbox | Barracuda | 284 | 82.6% |
| Mailbox | Microsoft 365 | 37 | 10.8% |
| Mailbox | EmailSecurity.app gateway | 6 | 1.7% |
| Mailbox | Mimecast | 5 | 1.5% |
| Mailbox | Proofpoint | 2 | 0.6% |
| Mailbox | Unknown / Other | 2 | 0.6% |
| ESP | Mailchimp | 50 | 14.5% |
| ESP | SendGrid (Twilio) | 44 | 12.8% |
| ESP | Amazon SES | 43 | 12.5% |
| ESP | Mandrill | 40 | 11.6% |
Gateway positioning and authentication pass-through
Barracuda Email Security operates as an incoming mail gateway for its customers, sitting between the public internet and the target organization's mailbox. For senders, this means SPF and DKIM validation happen at Barracuda's infrastructure before mail reaches the customer's own authentication systems. Your mail's reputation with Barracuda's filtering rules, not just your domain reputation, affects delivery to Barracuda-protected inboxes, and failures at the gateway level can reject mail before the recipient's server ever sees it.
See the full Barracuda Email Security data page (KPI cards, trend, sample domains) →
Run a free inbox-placement test across Gmail, Outlook, Yahoo and more — see exactly where your mail lands and why.
Frequently asked questions
What is Barracuda Email Security and do I need to worry about it when sending email?
Barracuda Email Security is a cloud-based email gateway that filters inbound mail for organizations. If your recipients use Barracuda, your mail must pass its filtering rules to reach their inbox — maintaining good sender reputation, avoiding spam triggers, and ensuring DKIM/SPF alignment will help your mail pass through.
How many domains use Barracuda Email Security?
344 domains in the Tranco top-1M use Barracuda Email Security as their email service provider (ESP) as of September 12, 2026 (0.05% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Is Barracuda Email Security common enough to affect email deliverability testing?
Barracuda Email Security 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 Barracuda Email Security most?
Barracuda Email Security's largest TLD is .com (34.0% of its domains); it appears across 35 TLDs in total.