I need to migrate from Courier IMAP to Dovecot IMAP.

Can Dovecot IMAP use two types of encrypted passwords on a virtual user's database password field?

I have database with a password field that is encrypted in MySQL format encrypt (MD5) so its limited to 8 chars and SHA-512. Courier is working with that and user can login using old encryption method and SHA-512 encrypted passwords.

Some users have old encryption and some users have new SHA-512 encryption.

Will this work for Dovecot IMAP?

Courier imapd has


What Dovecot should have?


default_pass_scheme = SHA512-CRYPT


auth default {
  mechanisms = digest-md5
  passdb sql {
    args = /etc/dovecot/dovecot-sql.conf

Will this work the same as it does for Courier?

1 Answer 1


see e.g. https://doc.dovecot.org/configuration_manual/authentication/password_schemes/

"The password scheme can be overridden for each password by prefixing it with {SCHEME}, for example: {PLAIN}pass."

So, you may just need to provide an appropriate scheme prefix with what you're importing from Courier.

Then see https://wiki.dovecot.org/HowTo/ConvertPasswordSchemes - which shows how you could re-hash an existing password to use a more secure hash.

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