If employees using personal email addresses receive Blink sign-in codes without issue but employees on your company domain do not, your organisation's email filtering is likely blocking delivery. This article covers how to fix it.
Why aren't Blink sign-in code emails reaching our users?
Your company's email security or spam filtering system is likely blocking emails from Blink's sending domain. Whitelisting joinblink.com in your email filter - or the sending IP address 198.2.136.138 - will allow OTP codes to reach users' inboxes.
✅ Why fixing this matters
• Prevents employees being locked out at scale - if OTPs aren't delivered, every user on your domain loses access to Blink simultaneously.
• One-time fix - whitelisting the domain or IP resolves the issue for all current and future users on your domain with no ongoing maintenance.
• Reduces support tickets - OTP delivery failure is one of the most common reasons employees contact IT about Blink access.
🔒 IT admin action required - the steps below need to be completed by whoever manages your organisation's email security or spam filtering system. This is not a setting within Blink.
🔍 How do I confirm this is the problem?
Before making changes to your email configuration, confirm that email filtering is the cause:
Ask an affected user to request a sign-in code to their work email address - confirm it doesn't arrive (including in spam).
Ask a user with a personal email address (e.g. Gmail) to request a code - if they receive it, the issue is specific to your domain's email filtering.
Check your email security platform's blocked or quarantined message logs for emails from joinblink.com.
⚙️ How do I fix OTP email delivery?
In your organisation's email security or spam filtering system, add joinblink.com to your allowlist (sometimes called a whitelist or safe senders list).
If domain-level whitelisting is not sufficient, also allowlist the sending IP address: 198.2.136.138.
Ask an affected user to request a new sign-in code. They should receive it within 60 seconds.
💡 Steps vary by platform. The exact process for adding an allowlist entry differs between email security providers (Microsoft Defender, Google Workspace, Mimecast, Proofpoint, etc.). Refer to your provider's documentation for specific instructions.
❓ FAQs
Only some users on our domain aren't receiving codes - why?
Only some users on our domain aren't receiving codes - why?
Filtering rules sometimes apply at a mailbox or group level rather than the whole domain. Check whether affected users are in a specific security group, have individual spam filters enabled, or are on a subdomain with different filtering rules. Reviewing quarantined mail logs for those specific users will usually identify the rule that's blocking delivery.
Does this affect SMS sign-in codes too?
Does this affect SMS sign-in codes too?
No. SMS and email OTP delivery are independent. If users aren't receiving codes by SMS, that is a separate issue - see Problems signing in to Blink for SMS troubleshooting steps.
We've whitelisted the domain but users still aren't receiving codes - what next?
We've whitelisted the domain but users still aren't receiving codes - what next?
Try also whitelisting the sending IP address 198.2.136.138. If that doesn't resolve it, contact Blink support with the name of your email security platform and the steps you've already taken - we can investigate from the sending side.
A user has unsubscribed from Blink emails - can they re-enable them?
A user has unsubscribed from Blink emails - can they re-enable them?
Yes, but this needs to be done by Blink support - it cannot be self-served by the user. Contact Blink support with the user's email address and we'll re-enable delivery.
🚀 What's next?
Related admin resources:
Helping a user who can't sign in - Helping a user who can't sign in to Blink
User-facing sign-in troubleshooting - Problems signing in to Blink
Inviting users to Blink - Inviting individual users