Mailock® With M365

Protect M365

email exchanges

Secure M365 emails with Mailock

Encrypt M365 emails and set recipient authentication challenges. Protect critical customer data exchanges.

Customer service rep securing M365 emails with Mailock

Microsoft 365 integration

Secure email tightly integrated with M365

Use our Outlook add-in for desktop secure email or our secure email gateway for high-volume contact and automated delivery.

  • Desktop add-in for individual secure emails
  • Exchange integration for scaled digital delivery
M365 outlook ribbon bar with Mailock secure email add-in

Recipient authentication

Challenge recipients,

protect information

Add multi-factor authentication to your M365 emails. Use SMS, question-and-answer, or Unipass ID challenges to verify recipients 'are who they say'.

Answering a Mailock secure email SMS challenge on mobile

Trigger words

'Before you send'

breach prevention

Customise our preset list of trigger words, which, if present in an unsecured email, will surface a prompt to send it securely.

Trigger word data breach protection in M365

Message revoke

Revoke you

can rely on

M365's native email recall tools work in a limited few scenarios. Mailock gives you the power to revoke secure messages unilaterally to contain a data breach.

Relieved at revoking a secure email at work using Mailock for M365


M365 & Mailock

Email with lock icon pink


Microsoft Purview Message Encryption

Prevent email interception
End-to-end encryption
Recipient authentication
Trigger words
Audit trails
Message revoke
Read notifications
Engagement analytics
High volume delivery

What's M365's

email encryption?

Top tier Microsoft 365 plans (e.g., E5) offer customers access to Microsoft Purview Message Encryption (MPME), part of the Azure Information Protection (AIP) suite. It uses email encryption to reduce the chance of an email getting intercepted.

Thanks Wealth Planning business team in board meeting laughing

When 365 isn't enough

As the team at Microsoft say, AIP is only designed to be used "to prevent accidental misuse and is not a security boundary." It lacks the authentication capabilities required to ensure delivery to the intended recipient and Microsoft actively discourages the use of encryption at high volumes.

Office with desktops using M365 secure email with Mailock

Regulatory compliance

Fulfil your obligations

Protect data in line with regulatory guidance

Encrypt personal information (GDPR)

The Information Commissioner's Office (ICO) and Financial Conduct Authority (FCA) require businesses to encrypt sensitive data transferred digitally. The ICO can levy fines of up to £17m for non-compliance (or 4% of turnover).

Record proof-of-delivery (MIFID II)

All businesses should record digital communications and retain proof-of-delivery to align with ICO guidance. Proof-of-receipt is also required by the FCA for certain types of document (e.g., KIDs).

Protect customers (Consumer Duty)

Are you encouraging customers to send their information into your business unsecured? The FCA's Consumer Duty is a mandate to provide easy-to-understand communications and protect customers from financial harm.


Mailock removes a lot of risk and GDPR concern..

... around dealing with everyone’s favourite communication method - email. We can send and receive our clients' information safely.

 Rob Hastings  Harwell Finance Group
IFA in meeting with client business about securing emails in M365

Easy Integration

Plug 'n' play

secure comms

Mailock works seamlessly with other 365 integrations, leaving your emails accessible to data loss prevention and server-side signature tools.

  • On-premise deployment support
  • Fully managed cloud service
Sending a secure email

Secure replies

Empower customers

to reply securely

Recipients can read messages and download attachments without creating an account, then connect their email to reply for free.

  • Customers read-and-reply free
  • Read-without-registration
Recipients can reply securely


Secure M365 emails.
Protect your data.

Turn email into a secure communications channel that drives customer engagement, efficiency, and carbon savings.

Encryption icon

End-to-end encryption

AES-256 end-to-end encryption obscures message and attachment data using military-strength ciphers.
Customer focus icon

Recipient authentication

Require recipients to authenticate themselves to open a secured message (e.g., SMS, Q&A, Unipass ID).
Data warning icon

Trigger words

Set custom keywords that trigger a warning if they appear in an email that's about to be sent unsecured.
Audit trail icon

Audit trails

Administrators and senders can view audit trails displaying send, read access, and download timestamps.
Revoke icon

Message revoke

Revoke access to secure emails regardless of recipient infrastructure (as a sender or an administrator).
Document icon

Read notifications

Read notifications tell senders when secure emails are opened regardless of recipient infrastructure.
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Engagement analytics

Tap into the Mailock API for accurate open rate and attachment download analytics for reporting.
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High-volume delivery

High-volume delivery means no imposed hard ceilings on volume or throughput (package dependent).

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Add multiple tenants to a single appliance to deliver secure email on behalf of multiple domains/brands.
Branding icon

Custom branding

Persist your branding throughout the secure email read experience, from email notification to web app.

Scaled delivery

Send secure email

at high volume

Do you need to secure email exchanges between contact centre and customer, or switch your confidential output from print-and-post to digital delivery, securely? There is no imposed hard ceiling on volume for Mailock Automated customers.

male IT professional on smartphone and laptop using automated secure email

Download the Complete Mailock & Microsoft 365 Guide

team sitting in common area in meeting

Increase efficiency

Save time spent sending sensitive information back and forth between colleagues, partners, clients and customers. Speed is key to a positive customer experience according to PWC reports.

weekend volunteers recycling in the park (3)

Save paper

Let’s reach Net Zero goals together, with innovation. Reduce your paper document output by taking sensitive document exchanges digital. Save carbon and do it with bottom line impact.

Woman in office securing professional emails on laptop at desk (1)

Protect data

Free your business from open-risk email. Protect messages and files from cyber threat and human error. Exchange documents with customers and keep their data safe in line with GDPR.

Mailock vs Microsoft 365 encryption meeting in office

Mailock compared

Read the review: M365 secure email vs Mailock

Read our review comparing Microsoft 365's secure email features with Mailock.

Case studies

  Hear from our users

6 min read
Rapport financial strategists
05 05 23

Boosting Security And Engagement At Rapport Financial Strategists

Rapport Financial Strategists improved the security and effectiveness of their client communications at an affordable price, using Mailock secure email.

2 min read
Woman speaking to colleague in office about email security
22 02 23

Brearley Law Puts The Protection Of Client Data First With Mailock

Brearley Law prioritises client data protection with Mailock. Discover how they successfully increased cybersecurity and built trust with their clients.

2 min read
Securing client communications at Stonebridge Financial
21 12 22

Securing Client Communications At Stonebridge Financial

Stonebridge Financial secured their email communications using Mailock, driving efficiency and engagement with their clients in the process.