BT Email - best practices for postmasters and senders of email

The main aim of BT's email service is to deliver messages that our customers want to receive and to filter out those messages that they don't, so they don't get loads of spam. We're always looking at ways to improve online security.

Please note: The advice you’ll find here is not intended for BT’s consumer customers but for senders of bulk emails to BT customers. If you are a BT business customer sending bulk emails, you should follow this advice. 

The main aim of BT's email service is to deliver messages that our customers want to receive and to filter out those messages that they don't, so they don't get loads of spam. We're always looking at ways to improve online security. That's why we've launched a new security feature designed to stop millions of spam emails in their tracks. It's based on an email security standard known as DMARC.

Many 3rd party senders are now DMARC compliant. However, if you do get a non-deliverable receipt for your email, please let the sending agency know. Ask their advice on how to send compliant emails through them. You can also drop a note to to advise of the problem.

We've improved our security to detect 'fake' emails that appear to come from legitimate domains but actually originate from somewhere else. So if you send lots of emails to BT customers with email addresses ending in, or - or share an emailing service that does - the best way to make sure your messages are delivered is to avoid looking like a spammer.

Just so you know, we don't support or maintain white lists, so don't be disappointed when we decline to add your domain to one.

Here's what to do so your emails aren't mistaken as spam.


Almost all email sending problems can be eliminated by following some basic set-up steps which unfortunately some commercial email service providers overlook. If you're unsure how to check these guidelines, speak to the support team that run your email service.

  1. Use a consistent and meaningful 'From' header address
  2. Make sure the domain you send from has a Sender Policy Framework (SPF) record for the IP address you'll be sending from. An SPF record allows domain owners to publish a list of IP addresses that are authorised to send email on their behalf. The aim is to reduce the amount of spam by making it harder for malicious senders to disguise their identity
  3. Make sure the IP address you send from is a static IP and not a dynamically assigned IP address
  4. Have separate IPs and streams depending on your email content type. Shared email services can have multiple domains using one IP to send email. If the same IPs are sending unsolicited commercial email along with your valid email, this can affect your reputation
  5. Make sure there is a correct PTR (reverse DNS entry) for your IP address. Reverse DNS is a method of resolving an IP address into a domain name, just as the domain name system (DNS) resolves domain names into associated IP addresses. If a spammer uses an invalid IP address that doesn't match the domain name, a reverse DNS look up program will try to match this to an IP address. If no valid name is found to match the IP address, the server blocks that message
  6. Sign all your email using DKIM. This protects recipients against spoofing and phishing. If you don't have a DKIM entry in your DNS or don't sign your email with DKIM we're more likely to consider it spam
  7. Check your email service has a good reputation
  8. Check your email sending service hasn't been blacklisted
  9. Don't send all your emails at once: split your mailing activity throughout the day

Along with this advice, we also recommend:

  • Keeping your email platform updated with the latest security patches
  • Filtering user-generated content before sending it as this prevents spammers from using your resources
  • Not allowing your servers to act as "open proxies" or "open relays". Spammers may attempt to send their own mail from your systems
  • Making sure your SMTP servers identify the originating IP addresses of the email and indicate this in the email headers; this can help you diagnose spam problems

Once you've eliminated the most common configuration issues, you'll then need to check the content of your email.

  1. Make sure your emails can be read if images are blocked
  2. Make sure you link to domains, never IP addresses
  3. Use standard ports
  4. Don't use HTML forms in your emails
  5. Don't use JavaScript or embed objects (like Flash or ActiveX)
  6. Always use a static 'From' address as this helps recipients who have set up filters to route emails to a specific folder

If your messages are being blocked, look closely at any SMTP error codes coming back from our mail servers and make sure you're addressing the problem. In our experience, commercial email services that comply with these principles have no problem in sending email to BT customers.

It's important to manage and update your mailing lists frequently as this can also help your sending reputation.

  • Monitor hard and soft bounces as well as inactive recipients. Sending emails to these addresses will result in your connections being deferred or blocked
  • Consider periodically sending a reconfirmation email to inactive subscribers. Or just remove them entirely
  • Sending email to users who are not reading them, or who mark them as "spam," will hurt your delivery metrics and reputation
  • Send email only to those who want it
  • Use and honour an opt-in method of subscription for your mailing list. Make sure subscribers have actively verified their intent to receive your mailings
  • Honour the frequency of your list's intent. Don't start sending daily emails to subscribers of your monthly mailing
  • Honour user requests to unsubscribe quickly
  • To stop your emails being treated as spam, think carefully about the subject line
  • Where possible, include any links as plain text rather than hyperlinks

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