Adding a key Use the following steps to create a DKIM signing key on the page Settings > Inbound/Outbound > DKIM Settings: Steps From the section DKIM Signing Keys, click Add. The Add Signing Key page displays. In the text field Key name, enter a name for your key. Select one of the following options for creating your key: Generate key to create the private keyThis is the default. The only option for key length is 1024 bits. See this Knowledge Base article to increase key length to 2048. Private key to enter a key you have already created Paste the key in the entry box. Click OK. The key is saved and displays in the section DKIM Signing Keys.