Apps Related to Address book integration

MicroSIP is a free, portable SIP softphone for Windows, renowned for its lightweight design and focus on security. It allows users to make secure audio and video calls over the internet using the SIP protocol, supporting various codecs and providing features like encryption and presence.

Telephone is a user-friendly SIP softphone application for macOS that enables encrypted voice calls over the internet or a private network. It supports various codecs and offers features like call recording, address book integration, and secure communication.

KMail is a powerful and flexible email client tightly integrated with the Kontact personal information manager suite. Part of the KDE ecosystem, it offers robust features for managing your email, including strong encryption options, support for multiple protocols like IMAP, POP3, and Exchange, and seamless integration with other Kontact components like the calendar and address book.

Mutt is a highly configurable, text-based email client for Unix-like systems. It offers powerful features for advanced users who prefer a lightweight and efficient email management experience directly from the command line.