How to use a single DKIM private key to sign all outbound mail going through an account

By following these instructions you can have a single DKIM key sign all outbound messages going through an account, regardless of what the From or Sender domain may be.

  1. You will need to add a single DKIM key to the account.  Fill out the domain, select, and other settings as usual.

  2. Using a text editor, edit the accounts general.config file and add a DKIMIdentity value within the [other] section of this file.  This file is located under the accounts/config directory.

For example, the below value would be set, if your DKIM key's domain were


DKIMIdentity =

  1. Once you have made these changes, you will need to reload the
    account settings.

The account will now sign every outbound message going through it with the specified DKIM key.  It will add an Identity parameter to the signature header, informing the recipients' server of the signing domain so that it can correctly get the public key.

*Note: The identity option will only work for DKIM and domain keys.