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Email encryption software falls into four categories. Client-side plug-ins, SMTP relays, enterprise gateways, and native platform features. Each fits a specific team size and compliance requirement.
Choosing email encryption software starts with the mail platform already in use, the number of users, the volume of regulated content, and the recipient technical setup.
This guide walks through each category and the practical criteria for choosing between them.
Client-Side Plug-Ins Add Encryption Inside the Mail Client
Client-side plug-ins install inside Outlook, Gmail, or Apple Mail and add encryption to the compose interface. Mailvelope adds PGP to browsers. Virtru and similar third-party plug-ins add portal-based encryption to Gmail and Outlook.
Native S/MIME support in Outlook and Apple Mail also functions as a client-side plug-in path when combined with an installed certificate. The user clicks Sign or Encrypt on a per-message basis.
Plug-ins suit small teams that want encryption without changing the mail platform. Deployment installs on each user machine or account. Training is per-user because encryption depends on user action.
The tradeoff is that plug-ins require user action for every sensitive send. A forgotten click means an unencrypted send with regulated content, which is a documented HIPAA breach cause.
SMTP Relays Intercept Mail at the Transport Layer
SMTP-relay services sit between the sender mail client and the recipient mail server. The sender configures outbound SMTP to route through the relay. The relay applies encryption and forwards to the destination.
Purpose-built HIPAA-compliant services often use this model. Mailhippo works this way. The sender writes and sends from Gmail or Outlook as usual. The relay handles encryption, TLS delivery, and portal fallback when TLS is unavailable.
The advantage is enforcement. Every outbound message routes through the relay and gets encrypted. The user cannot forget because there is no per-message action to remember.
The tradeoff is that the relay must be trusted with plaintext during the encryption step. The vendor signs a BAA and provides access logs for audit, but plaintext transit through the service is part of the design.
Enterprise Gateways Inspect and Enforce at Scale
Enterprise email gateways from Cisco, Proofpoint, Barracuda, and Mimecast sit inline with the mail server. Every outbound and inbound message passes through the gateway for inspection.
Data loss prevention rules scan outbound content for regulated patterns like Social Security numbers, medical record numbers, or payment card numbers. Matching messages are encrypted or blocked according to policy.
Gateways suit hospital systems, large financial firms, and government agencies. Setup involves integration with the mail server, policy configuration, and ongoing tuning to reduce false positives. Administrator time is significant.
For small and mid-sized practices, gateway software is often more infrastructure than needed. A relay-based service delivers the enforcement benefit without the operational overhead.
Native Platform Encryption Depends on the Tier
Microsoft 365 and Google Workspace include native encryption features on specific tiers. Microsoft 365 Business Premium and higher include the Encrypt button and Microsoft Purview Message Encryption. Google Workspace Enterprise Plus includes S/MIME hosted encryption.
Lower tiers do not include these features. Microsoft 365 Business Basic and Business Standard rely on TLS transport and do not offer the Encrypt button. Google Workspace Business Standard and Business Plus rely on TLS and Confidential Mode.
Native platform encryption is often the lowest-cost path when the organization already pays for a qualifying tier. It removes the need for third-party software. The setup is contained within the existing platform administration.
According to Microsoft documentation, Purview Message Encryption meets HIPAA transmission requirements when paired with a signed BAA. The BAA is included with qualifying Microsoft 365 tiers.
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S/MIME Software Requires Certificate Management
S/MIME implementations run as native components of Outlook, Apple Mail, and Gmail on Workspace Enterprise. There is no separate S/MIME software to install beyond the certificate itself.
The certificate lifecycle is where the operational cost lives. Certificates come from a trusted authority such as DigiCert, Sectigo, or IdenTrust. They expire after one to three years and need renewal. Departing employees need their certificates revoked.
Enterprise deployments automate the certificate lifecycle through a managed public key infrastructure. Small practices typically manage certificates manually per user, which is manageable for a few users but scales poorly.
PGP Software Is Free but Requires Technical Users
PGP is open source. The GNU Privacy Guard command-line tool and its front ends including Gpg4win on Windows, GPG Suite on Mac, and Mailvelope for browsers are free to install and use.
PGP does not use a certificate authority. Users generate a public-private key pair, share the public key with correspondents, and encrypt with the recipient public key. There is no annual certificate cost.
The trade-off is user experience. PGP requires understanding key exchange, verifying key fingerprints, and managing a keyring. Non-technical users find the workflow confusing. This limits PGP to teams that can standardize on it.
HIPAA Software Requires a Signed BAA
For HIPAA, the software vendor must sign a business associate agreement covering the handling of protected health information. This is a legal requirement, not a technical one. Software with strong encryption but no BAA does not qualify for HIPAA-scoped transmissions.
Purpose-built HIPAA services include the BAA in the base plan. Microsoft and Google sign BAAs at qualifying tiers. Some plug-in vendors sign BAAs on higher tiers or by request. Free tools generally do not.
According to HHS guidance, the BAA must specify permitted uses and disclosures, safeguards required, and breach notification obligations. Standard BAAs from established vendors cover these terms without custom negotiation.
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Integration Points Determine Deployment Time
The deployment time for encryption software depends on the integration point. Native platform features are already integrated; enabling takes minutes. SMTP-relay services require an outbound SMTP configuration change, typically completing in an hour. Client-side plug-ins install per user, so time scales with user count.
Enterprise gateways require the most setup. Integration with the mail server, policy design, testing, and rollout typically take weeks. Small teams almost never justify this scope.
- Native platform features: minutes to enable, no user-side setup.
- SMTP-relay services: hours to configure, no user-side setup.
- Client-side plug-ins: minutes per user, scales with user count.
- Enterprise gateways: weeks to deploy, requires ongoing policy tuning.
For small practices switching to encrypted email for the first time, the SMTP-relay path is typically the fastest to production with the fewest ongoing surprises.
Recipient Experience Shapes Adoption
The best encryption software fails if recipients cannot open the messages. Recipient friction is often the deciding factor between two otherwise comparable products.
S/MIME and PGP require the recipient to have keys installed and a supported client. Portal-based services require a click, a passcode, and a browser. Native platform encryption between users on the same platform requires no action.
For healthcare practices sending to patients, portal-based delivery is the standard. Patients cannot be expected to install S/MIME certificates or generate PGP keys. A one-click portal fits the workflow.
Test the recipient experience with a real recipient before choosing the software. Some corporate mail gateways strip portal links or block third-party domains. Testing surfaces those issues before deployment.
Choose Software That Matches the Existing Workflow
The final selection depends on user count, mail platform, compliance requirement, and recipient technical setup. The right software integrates with the platform already in use rather than requiring a switch.
- Team under 10 users, Gmail or Outlook, HIPAA scope, external patients: purpose-built SMTP-relay service.
- Team on Microsoft 365 Business Premium or higher, mixed recipients: native Encrypt button plus optional service for high-volume external.
- Enterprise with S/MIME infrastructure, internal certified users: native S/MIME on Outlook or Workspace Enterprise Plus.
- Large regulated organization, high message volume, DLP requirement: enterprise gateway with policy-based enforcement.
Sibling guides cover related considerations in what is the best email encryption software and HIPAA-compliant email software. For teams pairing email security with patient-facing infrastructure, resources on healthcare website security features add context.
The one-line summary is that the best email encryption software is the one that enforces encryption without breaking the workflow. Choose for enforcement, integration, and BAA coverage before feature lists.
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