SAP Knowledge Base Article - Public

2723259 - Server Side Synchronization fails with "ISSM-004: Foreign customization detected in user's mailbox"


End user synchronization fails with an error "ISSM-004: Foreign customization detected in user's mailbox - set by instance XYZ", where XYZ is the tenant URL.


SAP Cloud For Customer

Reproducing the Issue

  1. Login to system.
  2. Navigate to E-mail Integration work center.
  3. Navigate to user settings, you observer the error.


Issue occurs because user's mailbox was already initialized on different tenant previously. Initial tenant URL is shown in the message. Potential case - if user with the same mailbox switches from test to production tenant.


To resolve the issue,2 methods can be used.

Method 1 (recommended):

  1. If you still have access to initial tenant, which is shown in the message, log-on to that tenant as a key user.
  2. Go to Groupware Settings.
  3. Go to Users tab and find a user, who is getting the error.
  4. Click Gear icon in top right-hand side and click Reset mailbox.
  5. When completed, log-on to the new tenant and start synchronization.

Method 2:

  1. Log-on as a key user on affected tenant.
  2. Find affected user.
  3. Click Gear icon in top right-hand side and click Re-initialize User's mailbox.
  4. Start synchronization.
  5. If synchronization still works on the initial tenant - the same error will occur on that tenant.


"ISSM-004: Foreign customization detected in user's mailbox""Server Side Integration""Email""Error""ISSM-004" , KBA , issm-004 , LOD-CRM-GW-SCC , Invisible CRM - Smart Cloud Connect Solution , Problem


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