Penguin Mail is an open-source Linux app that connects Gmail, Microsoft accounts and standard mail servers while also handling calendars and contacts. It communicates directly with providers without its own relay server. AI is disabled until a model is selected, and local models are supported. According to its privacy policy, choosing external Claude sends the email content needed for a request to Anthropic; content may also be sent to web search and added MCP tools. Tokens are stored in a keyring, but the local mail database has no additional encryption, so full-disk encryption is recommended. Scheduled sending requires the app to remain running.