Voicemail-to-email is now a standard feature across most modern phone systems. Whether you’re using hosted VoIP, UC platforms, or a cloud PBX, the process is simple:

Miss a call → receive the voicemail instantly in your inbox.

However, across the industry, businesses are increasingly reporting that voicemail notifications are:

• Going to Junk
• Being placed in Quarantine
• Or not arriving at all

Importantly, this isn’t an issue with one specific phone system.

It’s a common challenge across almost all voicemail-to-email platforms — and it tends to occur most frequently in organisations using Microsoft 365 email.

Why This Is Happening

Most voicemail-to-email systems work in a similar way:

• An email is automatically generated when a voicemail is left
• An audio file (WAV or MP3) is attached
• The sender address is dynamically generated
• The email originates from a cloud mail server

From an email security perspective, that combination can sometimes look unusual.

Advanced filtering systems are designed to be cautious. If something doesn’t look typical, it may be flagged.

Why It Happens More Often in Microsoft 365

Microsoft has significantly strengthened email security within Microsoft 365 in recent years.

The platform includes:

• Advanced spam filtering
• Anti-phishing detection
• Attachment scanning
• Domain reputation analysis
• Impersonation protection

This is excellent from a security standpoint — phishing and email-based attacks are at record levels.

However, the downside is that automated system emails, including voicemail notifications, can sometimes be treated as suspicious.

Microsoft’s filtering engine may flag voicemail emails because:

• The sender address changes dynamically
• The sending domain may not yet have strong reputation history
• The email includes an attachment
• The message originates from cloud infrastructure

In most cases, these are false positives — but Microsoft errs on the side of caution.

This Is an Industry-Wide Issue

We see this across multiple voicemail-to-email platforms, not just one provider.

Microsoft 365 simply has stricter filtering policies compared to many other email platforms.

Microsoft is clearly prioritising protection — which is understandable — but it can sometimes be a little restrictive for legitimate system-generated emails.

Guidance for Tawk UC Customers

For tawk UC voicemail notifications, the sender address is dynamically generated.

The email address will appear as:

The caller’s telephone number, followed by either:

• @7el.co
• @tawk.network

For example:

• [email protected]
• [email protected]

Because the prefix changes based on the caller’s number, it is not possible to whitelist a single static email address.

To ensure reliable delivery, both domains should be whitelisted:

• 7el.co
• tawk.network

This principle applies to most voicemail-to-email systems that use dynamic sender addresses.

How to Whitelist Voicemail Emails in Microsoft 365 (2026 Guide)

The correct solution is to configure allow rules at tenant level.

Method 1: Use the Tenant Allow/Block List (Recommended)

1. Log into the Microsoft 365 Defender portal at security.microsoft.com
2. Go to Email & collaboration
3. Select Policies & rules
4. Open Threat policies
5. Choose Tenant Allow/Block List
6. Add the domains:
   • 7el.co
   • tawk.network

This tells Microsoft 365 that emails from these domains are trusted.

Method 2: Create a Mail Flow Rule (For IT Administrators)

If voicemail emails are still being quarantined:

1. Open the Exchange Admin Center
2. Go to Mail flow → Rules
3. Create a new rule

Configure the rule:

Apply this rule if:
Sender domain is 7el.co
OR
Sender domain is tawk.network

Do the following:
Modify message properties → Set Spam Confidence Level (SCL) to -1

This bypasses spam filtering for those domains.

Why Outlook Safe Senders Is Not Enough

Adding an address to Safe Senders in Outlook:

• Only affects user-level junk filtering
• Does not override Microsoft Defender quarantine policies

For business environments, tenant-level configuration is the correct approach.

The Business Impact of Quarantined Voicemail Emails

If voicemail notifications are being filtered or quarantined, businesses may experience:

• Missed customer messages
• Delayed call-backs
• Lost sales opportunities
• Increased IT support tickets

A simple whitelist configuration resolves the vast majority of these issues.

Final Thoughts

Voicemail-to-email delivery issues are now common across the industry — particularly within Microsoft 365 environments.

This is not a fault with your phone system. It is typically the result of increasingly aggressive email security filtering designed to protect users from phishing and malware threats.

The good news is that with the correct allow configuration in place, delivery becomes reliable and consistent.

If your organisation is experiencing voicemail emails going to Junk or Quarantine in Microsoft 365, please share this post with your IT team so they can review and apply the recommended configuration.