An external email app authenticates to LightDrive IMAP and SMTP with a dedicated Email client password. Your main Vault password and Vault app passwords do not authenticate to email.
Create the credential under Settings → Security → App & device access. Name it for one device and app, choose its access, copy it when LightDrive displays it, and enter it as the normal password for both IMAP and SMTP. The value is shown only when created.
- Email & contacts: use with a compatible app such as Thunderbird that can connect to IMAP, SMTP, and CardDAV.
- Email only: use when the app needs only IMAP and SMTP.
An Email & contacts password can also connect to the LightDrive CardDAV address book. An Email-only password cannot. Neither type can sign in to the Vault or connect to Files or Calendar. Protect the device and revoke its client password immediately if the device is lost or retired.
Changing the main Vault password does not change an existing Email client password. If a mail app stops authenticating, confirm that the credential has not been revoked and create a replacement if needed.