# Why do I need to install a certificate when configuring Apple Mail with Bridge?

Apple Mail requires a secure channel for communications with email servers, and the server needs to be acknowledged as trusted.

In order to communicate with Bridge, Apple Mail requires secure connections using SSL/TLS. This cryptographic protocol includes an identity verification system using certificates. For publicly available servers, certificates are normally issued and digitally signed by a certificate authority, such as Let's Encrypt. This is not possible for Bridge, as the IMAP and SMTP servers are running on your own computer, and are not accessible from any network (local or internet).

The solution is to use a self-signed certificate. When setting up an email account where the server provides a self-signed certificate, most email clients will issue a warning asking you whether you trust the server or not, because the certificate was not issued by a certificate authority.

Apple Mail requires an extra step. It will simply refuse to connect if the certificate is not set as trusted. Bridge solves this by storing this certificate in the macOS keychain. This operation requires that you provide your macOS account password.