According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), 123-reg (UK) is the mailbox provider for 189 domains — 0.03% of 658,711 domains with MX records. Detection method: primary MX record (lowest preference).
123-reg is a UK-based domain registrar and web hosting provider that operates email infrastructure for its customers' registered domains. It primarily serves small to medium-sized businesses and operates globally, hosting email, domains, and web services for many SMB customers.
In email deliverability terms, 123-reg occupies the long tail of smaller, non-enterprise domains rather than the largest global brands. Its footprint is globally distributed across many top-level domains, with notable presence in the US market. Because 123-reg frequently appears alongside SendGrid in customer infrastructure, senders and filtering systems encounter its mailboxes and authentication requirements regularly when dealing with diverse, SMB-focused recipient bases.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 0 | 0.0% |
| Top 100,000 | 10 | 5.3% |
| Top 1,000,000 | 130 | 68.8% |
| Unranked | 49 | 25.9% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 80 | 42.3% | |
| .co.uk | 56 | 29.6% | |
| .net | 11 | 5.8% | |
| .org | 11 | 5.8% | |
| .org.uk | 10 | 5.3% | |
| .club | 2 | 1.1% | |
| .online | 2 | 1.1% | |
| .co | 2 | 1.1% | |
| .us | 2 | 1.1% | |
| .uk | 1 | 0.5% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 189 domains.
| Type | Service | Domains | Share of 123-reg (UK) users |
|---|---|---|---|
| ESP | SendGrid (Twilio) | 6 | 3.2% |
| ESP | Amazon SES | 5 | 2.6% |
| ESP | Mailgun | 2 | 1.1% |
| ESP | Mandrill | 2 | 1.1% |
| ESP | Adestra (MessageFocus) | 1 | 0.5% |
| ESP | Mailjet (Sinch) | 1 | 0.5% |
| ESP | SparkPost | 1 | 0.5% |
| ESP | Brevo (ex-Sendinblue) | 1 | 0.5% |
| ESP | Campaign Monitor | 1 | 0.5% |
| ESP | Zoho Campaigns | 1 | 0.5% |
Many 123-reg domains maintain inbound mail at 123-reg whilst routing outbound campaigns through SendGrid or similar third-party services. This split-service model requires both the primary mailbox provider and the outbound service to be authorised in the domain's SPF record and properly configured for DKIM signing. Misconfigurations in this arrangement—incomplete SPF policies or inconsistent authentication setup—are a common source of deliverability failures among 123-reg customers.
See the full 123-reg (UK) data page (KPI cards, trend, sample domains) →
Yes; 123-reg hosts mail for a substantial segment of small-to-medium business domains, making it a representative test target for senders reaching diverse, non-enterprise recipient bases.
189 domains in the Tranco top-1M use 123-reg (UK) as their mailbox provider as of July 13, 2026 (0.03% of domains with MX records), according to Live Direct Marketing's daily DNS scan.
123-reg (UK) accounts for 0.03% of domains with MX records 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.
123-reg (UK)'s largest TLD is .com (42.3% of its domains); it appears across 22 TLDs in total.