If you need to disjoin your MailGate with Secure Mailbox High Availability (HA) cluster and eventually join in back, you will need to follow the steps provided below.

Otherwise, you will receive an error message when you try to join the secondary server(s) to the primary again.

PREREQUISITES:

1. Make sure there is no mail flow or end user activity
2. Go to sm_notifications folder on the external storage. There should be two folders named like the appliance IDs of the primary and secondary server(s). Make sure there are no files in either of these folders. If there are, please wait a bit until they are automatically processed and cleared

STEPS:

1. Disjoin the secondary server(s) from the primary
2. Go to sm_notifications folder on the external storage. In the folder named as the secondary appliance ID there should be only one file named disjoin. Delete it
3. Join the secondary server(s) back to the primary.