# Why do I need bridge?

Proton does not have access to the content of your messages, so it cannot share your unencrypted messages with your email client from the Proton servers.

Email clients such as Microsoft Outlook, Mozilla Thunderbird and Apple Mail use standard protocols named IMAP and SMTP to receive and send emails.

Even though the IMAP and SMTP protocols can use secure channels (using SSL/TLS), they do not offer support for encrypted messages. Because Proton does not have access to the content of your messages, it is not possible to configure your email client to connect directly to Proton servers.

The key to solving this problem is Bridge. Once installed on your computer and connected to your Proton account, Bridge can access your encrypted messages stored on the Proton servers. Bridge integrates an IMAP and a SMTP server that run on your computer and are accessible only to applications executing on your machine. Your email client connects to these local servers and Bridge is responsible for seamlessly encrypting and decrypting the messages that you send and receive.