When you send pensions, legal files, or identity documents by email, the practical question is how messages are encrypted, who can open them, and what evidence you keep afterwards.
We’ll look at how two popular secure email services compare: Mimecast’s email security suite and Mailock.
We’ll explore how they support outbound email security across:
Mimecast: Secure message recall or earlier expiry can be available to senders or administrators, depending on configuration and permissions.
Mailock: Recall even after the recipient has opened the message.
Free Read-and-Reply
Mimecast: Recipients access messages through the Mimecast secure web portal.
Mailock: Recipients can read without registration. Replies require a free account.
Read Receipts and Audit Trail
Mimecast: Read receipts available, full audit trails not included in core messaging service.
Mailock: Full audit trail with automatic read notifications and attachment tracking.
What Is Mimecast?
Mimecast is a cybersecurity provider focused on protecting businesses from email-based threats such as phishing, malware, and data loss.
Its secure messaging service helps organisations protect sensitive data and ensure regulatory compliance by encrypting outbound messages and monitoring access.
Headquartered in London, Mimecast serves a global customer base with email security, continuity, and archiving solutions.
Mimecast: Outbound Security Features
Encryption
Mimecast uses AES-256 encryption and allows administrators to apply it based on content or recipient rules.
Senders can set expiry dates, subject to configuration. Businesses needing long-term access records should check what is included in their Mimecast setup.
Message Recall
Mimecast documentation says a secure message can be recalled or expired earlier than the configured expiry date by either the sender or a Mimecast administrator with the right permissions.
Recipient Verification
Mimecast secure messages are accessed through a secure web portal. Buyers that need sender-controlled recipient identity challenges should confirm whether their chosen Mimecast configuration supports that workflow.
Read Receipts and Auditing
Read receipts are available on request. Full auditing is not included in the core secure messaging product.
Branding
Admins can apply corporate branding, including logos, colours, and company names. These are managed through a central console and can be toggled by message type.
User Experience and Integrations
Mimecast integrates with Outlook, its own portal, and a mobile app. Users can initiate encryption via security alerts or set rules.
Recipients do not need to download software, but they access protected messages through the Mimecast secure web portal.
Mimecast holds a customer rating of 4.3 on Capterra, based on 80 reviews checked on 3 June 2026.
Customer Support and Pricing
Mimecast offers support through knowledge articles, video guides, and community forums. Direct assistance is available depending on your plan.
Mimecast does not publish clear standard pricing for this secure messaging use case on its product page. Organisations should request current pricing for their deployment.
Free trials and demos are available on request.
What Is Mailock?
Mailock, developed by Beyond Encryption, is a secure email solution that protects sensitive information through encryption and recipient verification.
It enables organisations to reduce print and postal costs, meet regulatory requirements, and prevent data loss when sending confidential messages by email.
Mailock is widely used across financial services, legal, and accounting sectors to secure communications and demonstrate compliance.
Mailock: Outbound Security Features
Encryption
Mailock applies end-to-end AES-256 encryption, securing both message content and attachments.
Security policies can be set by admins or triggered by users via keywords. Key management ensures only intended recipients can decrypt a message.
Recipient Verification
Mailock offers layered authentication, ensuring messages are only accessed by verified recipients:
SMS: Sends a one-time code to the recipient’s phone.
Q&A Challenge: Customisable question only the recipient can answer.
Unipass ID: Digital certificate verification used in financial services.
Email verification: For low-risk messages where identity is already confirmed.
Message Recall
Messages can be recalled at any time - even if already opened - via the Mailock Outlook add-in or web interface.
Read Receipts and Audit Trail
Read notifications and a complete audit trail are included by default, showing who opened what and when, with full visibility on attachments.
User Experience and Integrations
Mailock is designed for ease of use. Recipients can read secure messages without needing to create an account. To reply, they can register for a free account with a limited number of secure sends.
The platform integrates with Microsoft 365 via an Outlook add-in and supports secure web access.
Customer Support and Pricing
Mailock offers personal support during setup and everyday use, rated 4.7 on Capterra, based on 63 reviews checked on 3 June 2026. A demo and free trial are available.
There are three licence options:
Free: Limited sends, read receipts, Q&A authentication, Outlook add-in.
Mailock fits teams that need strong outbound email protection: recall after open, layered authentication, and a recipient path that does not require registration to read.
You can use Mimecast and Mailock together rather than treating them as either/or choices.
Sabrina McClune writes about cybersecurity, data protection, digital identity, and digital transformation for Beyond Encryption, helping regulated sectors understand complex technology and compliance topics with greater clarity.
Sabrina McClune
.svg)
Previous post