three.co.uk - Email Domain Verification & Deliverability Report

Active ISP Email Provider
Organization: Three UK
Mail Server: Symantec/Broadcom
Verified 4 days ago

Real-time verification data for three.co.uk. View MX records, SPF/DKIM/DMARC authentication, and server deliverability status.

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MX Records for three.co.uk

PriorityMail ServerIP Address
10 cluster3.eu.messagelabs.com 195.245.231.73
20 cluster3a.eu.messagelabs.com 34.91.159.228
SMTP Status: Responding
SMTP Banner:
220 server-2.tower-870.messagelabs.comZ ESMTP

three.co.uk uses Symantec/Broadcom mail servers, which means emails are processed through Symantec/Broadcom infrastructure with their built-in spam filtering and security controls.

Email Authentication for three.co.uk

SPF Record Pass

v=spf1 a:spf.three.co.uk include:spf.messagelabs.com include:amazonses.com include:_spf.salesforce.com include:spf.mandrillapp.com include:eu.khoros-mail.com ip4:154.62.6.32 ip4:154.48.212.32 ip4:38.225.210.141 ~all
Authorized Senders:
spf.messagelabs.com amazonses.com _spf.salesforce.com spf.mandrillapp.com eu.khoros-mail.com

SPF (Sender Policy Framework) specifies which mail servers are authorized to send email on behalf of three.co.uk.

DMARC Record Quarantine

v=DMARC1; p=quarantine; sp=none; pct=100; rua=mailto:dmarc_agg@vali.email,mailto:dmarc@three.co.uk

Policy applied to: 100% of emails

DMARC (Domain-based Message Authentication) tells receiving servers what to do with emails that fail authentication checks.

DKIM Not Detected

DKIM detection is limited from external scanning. The domain may use DKIM with selectors not covered by our scan.

Authentication Summary: three.co.uk has SPF and DMARC configured. This provides good protection against email spoofing. Senders can expect reliable email delivery to this domain.

WHOIS & Domain Information

Registration Details

Domain
three.co.uk
TLD
.co.uk
Created
1997-04-15
Updated
2025-11-12
Expires
2027-04-15
Domain Age
28 years

Registrar

Name
CSC Corporate Domains, Inc [Tag = CSC-CORP-DOMAINS]
IANA ID
299

Name Servers

  • udns1.cscdns.net
  • udns2.cscdns.uk

About three.co.uk

three.co.uk is a UK ISP domain from Three UK, one of the UK's major mobile network operators owned by CK Hutchison. Three provides mobile and broadband services to British consumers.

three.co.uk implements SPF authentication. Compliant with UK GDPR.

The mail servers validate recipients and reject invalid addresses. The domain does not operate as catch-all.

For delivery, authenticate with SPF. Follow UK email regulations.

How to Verify three.co.uk Email Addresses

Need to check if an email address at three.co.uk actually exists before you send to it? BulkEmailChecker performs deep SMTP-level validation, connecting directly to three.co.uk's mail servers to confirm the mailbox is real, active, and able to receive your message. No test email is ever sent, so your sender reputation stays protected.

Verify a Single three.co.uk Email
Use BulkEmailChecker's free email verification tool to instantly validate any three.co.uk address. You'll get a complete deliverability report including mailbox existence, catch-all detection, disposable domain flagging, and risk scoring, all in under 3 seconds.

Verify a List of three.co.uk Emails in Bulk
Have a mailing list full of three.co.uk addresses? Upload your CSV or TXT file to BulkEmailChecker and verify thousands of email addresses in minutes. Our bulk verification engine runs 30+ checks per address including syntax validation, DNS resolution, SMTP handshake, and spam trap detection. Clean your list before every campaign to keep bounce rates below 2% and protect your sender score. See bulk pricing.

Verify three.co.uk Emails via API in Real-Time
Building a signup form, CRM integration, or lead capture system? BulkEmailChecker's real-time verification API validates three.co.uk email addresses at the point of entry, blocking invalid, disposable, and risky addresses before they enter your database. Integrate with a single API call and prevent bad data at the source.

Frequently Asked Questions

Yes, three.co.uk is a valid email domain provided by Three UK to its internet subscribers. It is a legitimate ISP-issued email address.
No, three.co.uk is not a disposable or temporary email provider. It is an ISP-provided email service tied to an internet subscription from Three UK.
three.co.uk uses mail servers operated by Three UK. Check the MX records section above for specific server details and authentication configuration.
Yes, you can send marketing emails to three.co.uk addresses with proper opt-in consent. ISP email providers apply spam filtering, and addresses may become inactive if subscribers cancel their internet service. Regular list verification is recommended.
Use BulkEmailChecker to verify three.co.uk addresses via SMTP checks. ISP domains may have specific rate limiting or greylisting behaviors. Our tool handles these provider-specific configurations automatically.
The fastest and most accurate way to verify a three.co.uk email address is to use BulkEmailChecker's free email verification tool. Simply enter the full email address and our system performs SMTP-level validation by connecting directly to three.co.uk's mail servers. You'll get instant results showing whether the mailbox exists, is deliverable, and is safe to send to, all without sending a single email.
Yes. BulkEmailChecker uses SMTP verification to check if a three.co.uk mailbox exists without ever delivering an email. Our system connects to the domain's mail server, performs an SMTP handshake, and queries the mail server to confirm whether the recipient address is valid. This process is completely invisible to the email recipient and does not affect your sender reputation.
Sending to invalid email addresses causes hard bounces, which directly damage your sender reputation. Internet Service Providers (ISPs) and email providers track your bounce rate, and if it exceeds 2%, your emails may start landing in spam folders or get blocked entirely. Verifying three.co.uk addresses with BulkEmailChecker before sending prevents bounces and keeps your deliverability high.
BulkEmailChecker's bulk verification service lets you upload a CSV or TXT file containing thousands of three.co.uk email addresses and verify them all at once. Each address goes through 30+ verification checks including syntax validation, DNS/MX lookup, SMTP verification, disposable domain detection, and spam trap identification. Results are typically ready within minutes and can be downloaded as a clean, verified list.
Email verification is the process of confirming that an email address is real, properly formatted, and capable of receiving messages. It matters because sending to invalid addresses causes bounces, damages your sender reputation, wastes marketing budget, and can get your sending IP blacklisted. BulkEmailChecker verifies addresses at the SMTP level, the most accurate method available, ensuring your emails reach real people.
MX (Mail Exchange) records are DNS entries that specify which mail servers are responsible for receiving email for a domain. When you send an email, your mail server looks up the recipient domain's MX records to find where to deliver the message. If a domain has no MX records, it cannot receive email. BulkEmailChecker checks MX records as part of every verification to confirm the domain is configured for email delivery.
A catch-all (or accept-all) domain is configured to accept email sent to any address at that domain, regardless of whether the specific mailbox exists. This makes it harder to verify individual addresses because the server always responds positively. BulkEmailChecker detects catch-all configurations and flags them in verification results so you can make informed decisions about sending to those addresses.
Yes. BulkEmailChecker offers a real-time email verification API that you can integrate into signup forms, CRM systems, lead capture tools, and any application that collects email addresses. The API validates addresses at the point of entry, blocking invalid, disposable, and risky emails before they enter your database. Integration takes just a single API call with response times under 3 seconds.

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