Personnaly, I use https://gitlab.com/shackra/goimapnotify , you can add a `~/.config/imapnotify/{{ youremailaddresshere }}.yaml` config file for each of your email addresses and enable and start it as a systemd service with `systemctl --user enable ---now goimapnotify@{{ youremailaddresshere }}.service`

Here is and example of a config file for a gmail address :

```

  host: imap.gmail.com
  port: 993
  tls: true
  tlsOptions:
    rejectUnauthorized: false
  username: {{ youremailaddresshere }}
  password: ''
  passwordCMD: pass mw/{{ youremailaddresshere }} | head -n1
  onNewMail: mailsync {{ youremailaddresshere }} | while read OUTPUT; do notify-send "" "$OUTPUT"; done
  onNewMailPost: ''
  onDeletedMail: ''
  onDeletedMailPost: ''
  boxes:
    - INBOX

```