Email clients and TLS trust

Connect any standard email client to MailCue and trust its self-signed CA so TLS handshakes succeed.

Using with email clients

MailCue works with any standard email client. Configure your client with:

Setting	Value
IMAP Server	`localhost` (port 143 or 993 for SSL)
POP3 Server	`localhost` (port 110 or 995 for SSL)
SMTP Server	`localhost` (port 587, STARTTLS)
Username	`admin@mailcue.local` (or any created mailbox)
Password	Your mailbox password
Security	Accept the self-signed certificate

TLS certificate

MailCue generates a self-signed TLS certificate at container startup for Postfix, Dovecot, and Nginx. Any application connecting to MailCue over TLS (mail clients, SMTP relays, CI pipelines) must trust this certificate. You can download it from the Admin UI (Admin > TLS Certificate tab) or via the API:

curl -o mailcue-ca.crt http://localhost:8088/api/v1/system/certificate/download

Then install it in your system trust store:

macOS

sudo security add-trusted-cert -d -r trustRoot \
  -k /Library/Keychains/System.keychain mailcue-ca.crt

Or double-click the file to open Keychain Access and set it to "Always Trust".

Linux (Debian/Ubuntu)

sudo cp mailcue-ca.crt /usr/local/share/ca-certificates/
sudo update-ca-certificates

Linux (RHEL/Fedora)

sudo cp mailcue-ca.crt /etc/pki/ca-trust/source/anchors/
sudo update-ca-trust

Windows

certutil -addstore -f "ROOT" mailcue-ca.crt

Or double-click the file and install to "Trusted Root Certification Authorities".

Docker / CI Pipelines

RUN curl -o /usr/local/share/ca-certificates/mailcue-ca.crt \
      http://<mailcue-host>/api/v1/system/certificate/download \
    && update-ca-certificates