An external email app authenticates to LightDrive IMAP and SMTP with a LightDrive client password that includes Email. Your main LightDrive 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.
Choose only the services the app needs. Other Email-enabled choices are Email & calendars and Email, contacts & calendars. A LightDrive client password can authenticate only the services selected when it is created; it does not sign in to the Vault or grant Files access. 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 LightDrive client password. If a mail app stops authenticating, confirm that the credential has not been revoked and create a replacement if needed.