It can be used to encrypt and sign electronic messages, including attached files, without the use of a separate, native email client (like Thunderbird) using the OpenPGP standard.

[7] For Chromium/Chrome there's the possibility to install from an authenticated source using the integrated software extension manager "Chrome Web Store".

[9] Since version 3.0, a local GnuPG installation can be included in Mailvelope's key management, allowing users to use native applications if desired.

In April 2015, De-Mail providers equipped their services with a default disabled option for end-to-end encryption based on Mailvelope, but it could only be used in combination with Mobile TAN or the German electronic identity card.

In August 2015, the email services of Web.de and GMX introduced support for OpenPGP encryption and integrated Mailvelope into their webmail applications for that.

They recommended integrating assistant functionality, sending instructive invitation messages to new communication partners, and publishing basic explanatory texts.

[16] The Mailvelope-based OpenPGP system of United Internet integrates such functionality and its usability earned some positive mentions in the press, particularly the offered key synchronization feature.

[17][9] A usability analysis from 2016 found it to still be "worthy of improvement" ("verbesserungswürdig"), though, and mentioned "confusing wording" ("irritierende Formulierungen"), missing communication of the concept, bad password recommendations, missing negative dissociation of the more prominent modus that features only transport encryption, plus insufficient support for key authenticity checking (to thwart man-in-the-middle attacks).

[19][20] According to the BSI, one goal of the project was also to enable website operators to offer contact forms in the future to securely encrypt messages from the user's browser to the recipient.