gpg4o

gpg4o is ranked #4 of 28 in email encryption software on The Geeks Club, made by gpg4o (Darmstadt, Germany). It runs on Windows. There is a free plan. A free trial is offered. Paid plans start at €99.95/mo.

gpg4o plans and pricing

All plans

gpg4o €99.95/mo All functions of the OpenPGP encryption system · Microsoft Outlook 2016/2019/2021/365 Classic bayoosoft.com · 20 Sept 2026

gpg4o Free Free Free version without a time limit · Functionality is limited download.giepa.de · 20 Sept 2026

gpg4o – Extension product maintenance 1 year €5,195/yr one year Updates and support for gpg4o bayoosoft.com · 28 Sept 2026

gpg4o – Extension product maintenance 3 years €13,995/yr three years Updates and support for gpg4o bayoosoft.com · 28 Sept 2026

gpg4o €9,995 once one-time license Microsoft Outlook 2016/2019/2021/365 Classic · OpenPGP functions bayoosoft.com · 28 Sept 2026

Compared on email encryption software

Free plan: Yes
Secure delivery: attachment
Recipient verification: identity
Message expiry: No
Outlook integration: Yes
Gmail integration: No
Admin access controls: Yes

Best gpg4o alternatives

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7.9 Lockbin Free plan

7.8 DataMotion Secure Email Exchange Free trial

7.7 Mailvelope Free trial €3/mo

7.0 Encryptomatic OpenPGP $2.50/mo

7.0 FlowCrypt Free plan

6.9 c.Email Free plan

gpg4o

Free plan: Yes
Secure delivery: attachment
Recipient verification: identity
Message expiry: No
Outlook integration: Yes
Gmail integration: No
Admin access controls: Yes
Product: gpg4o is a Microsoft Outlook add-in for encrypting, decrypting, signing and checking messages and attachments.
Encryption: It uses asymmetric encryption with private and public keys and follows the OpenPGP standard.
Outlook integration: The add-in provides end-to-end encryption directly through the Outlook interface.
Key management: Key Server Management supports automatic synchronization, local and public key servers, and Web of Trust checking; central management requires Enterprise KeyServer.
Compatibility: The maker lists compatibility with Symantec Encryption, Enigmail, KMail, Apple Mail, K9-Mail and iPGMail.
Enterprise features: gpg4o supports terminal servers, Microsoft Policy Manager, automatic key generation and working groups.
Mail formats: It supports encrypted HTML email, PGP/MIME and PGP/Inline.
Price from: €99.95/mo

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Where it ranks on The Geeks Club

Best Email Encryption Software in 2026#4 of 28
Best File Encryption Tools in 2026#7 of 27

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Sources

bayoosoft.com/en/gpg4o-en/gpg4o-email-encryption/;· checked 20 Sept 2026
bayoosoft.com/en/gpg4o-en/gpg4o-features/· checked 28 Sept 2026
bayoosoft.com/en/gpg4o-en/gpg4o-support/· checked 28 Sept 2026
bayoosoft.com/en/about-us/· checked 28 Sept 2026
bayoosoft.com/en/gpg4o-en/gpg4o-email-encryption/· checked 28 Sept 2026
download.giepa.de/gpg4o/6.0.124.9651/handbuch.pdf· checked 20 Sept 2026