According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Heart Internet (UK) is the mailbox provider for 121 domains — 0.02% of 658,711 domains with MX records. Detection method: primary MX record (lowest preference).
Heart Internet is a UK-based email and hosting provider serving small businesses, independent websites, and sole traders across the .co.uk domain and international TLDs.
Heart Internet's mailbox footprint is concentrated in the long tail of smaller websites rather than enterprise or major-brand domains. The frequent pairing of Heart Internet MX records with SendGrid infrastructure in audited domains suggests many Heart Internet customers use third-party mail services for outbound delivery whilst maintaining inbound mailboxes with Heart Internet. For senders and deliverability professionals, this hybrid architecture introduces authentication coordination demands: carefully aligning SPF, DKIM, and DMARC policies across both providers is essential to avoid downstream deliverability friction.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 1 | 0.8% |
| Top 100,000 | 7 | 5.8% |
| Top 1,000,000 | 83 | 68.6% |
| Unranked | 30 | 24.8% |
| TLD | Domains | Share | |
|---|---|---|---|
| .co.uk | 43 | 35.5% | |
| .com | 40 | 33.1% | |
| .net | 8 | 6.6% | |
| .ie | 6 | 5.0% | |
| .uk | 5 | 4.1% | |
| .org | 5 | 4.1% | |
| .info | 2 | 1.7% | |
| .org.uk | 2 | 1.7% | |
| .biz | 2 | 1.7% | |
| .press | 1 | 0.8% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 121 domains.
| Type | Service | Domains | Share of Heart Internet (UK) users |
|---|---|---|---|
| ESP | SendGrid (Twilio) | 7 | 5.8% |
| ESP | Mandrill | 6 | 5.0% |
| ESP | Mailgun | 6 | 5.0% |
| ESP | Mailjet (Sinch) | 5 | 4.1% |
| ESP | Mailchimp | 4 | 3.3% |
| ESP | AuthSMTP | 3 | 2.5% |
| ESP | Campaign Monitor | 3 | 2.5% |
| ESP | Amazon SES | 3 | 2.5% |
| ESP | Zendesk | 3 | 2.5% |
| ESP | SparkPost | 2 | 1.7% |
Heart Internet customers often delegate outbound mail delivery to commercial providers like SendGrid whilst hosting their domain's inbound mailboxes with Heart Internet. This division — where the MX record points to Heart Internet but outbound headers reference the third-party provider — requires close coordination of sender authentication standards. Without proper alignment of SPF, DKIM, and DMARC across both infrastructure points, legitimate mail can fail authentication checks and experience deliverability friction at downstream recipients.
See the full Heart Internet (UK) data page (KPI cards, trend, sample domains) →
Heart Internet is a UK-based mailbox provider for smaller businesses and independent websites, particularly in the .co.uk domain. Its prevalence in email audits reflects its widespread use across the long tail of smaller sites, often alongside third-party services like SendGrid for outbound delivery.
121 domains in the Tranco top-1M use Heart Internet (UK) as their mailbox provider as of July 13, 2026 (0.02% of domains with MX records), according to Live Direct Marketing's daily DNS scan.
Heart Internet (UK) accounts for 0.02% 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.
Heart Internet (UK)'s largest TLD is .co.uk (35.5% of its domains); it appears across 17 TLDs in total.