Managing and creating a multi-server deployment can be challenging when you start to look at all the roles you can associate to a server. When setting up a new deployment or working with an existing one it is always suggested to refer to the Microsoft Dynamics CRM Implementation Guide. The following suggestions should provide value on that next Server Side Sync hurdle.

Issue:

With Server Side Sync configured you may come across pending send mail if you have multiple email integration services in the same deployment

Cause:

One CPU tries to take on all the work an can create a backlog

Resolution:

1. Dedicate one backend server for mail processing

*this may not be an option where high availability is a concern*

2. Update the deployment properties table to throttle for better management

update MSCRM_CONFIG.dbo.DeploymentProperties set IntColumn =
'1'
where ColumnName =
'AsyncMailboxesPerEvent'

update MSCRM_CONFIG.dbo.DeploymentProperties set IntColumn =
'300'
where ColumnName =
'MailboxQueueItemsInMemoryHigh'

update MSCRM_CONFIG.dbo.DeploymentProperties set IntColumn =
'100'
where ColumnName =
'MailboxQueueItemsInMemoryLow'

update MSCRM_CONFIG.dbo.DeploymentProperties set IntColumn =
'10'
where ColumnName =
'MailboxQueueSelectInterval'

update MSCRM_CONFIG.dbo.DeploymentProperties set IntColumn =
'1'
where ColumnName =
'MailboxQueueSelectMaxItems'

*MailboxQueueSelectMaxItems start with 5 working your way down

**these adjustments are as/is and may need to be adjusted for your deployment

Happy CRM'ing!