Too many folders? Limits could slow Exchange migrations

Agencies with more than 10,000 public folders may have problems when they migrate to Exchange Server 2013 and Exchange Online. 

The issue was recently highlighted by Microsoft MVP Tony Redmond  who pointed out that organizations will find that Microsoft uses a different technology for public folders in newer versions of Exchange. However, Microsoft offers no easy way for such organizations to discover and clean up folders that may have been created and abandoned, while also identifying folders with information that should be retained.

Typically, moving public folders would be the last step in an agency’s Exchange migration, although it's not supported in some moves, such as moving from Exchange Server 2003 to Office 365.

Microsoft appears to have published the limits of public folders for Exchange Server 2013 late last month. Prior to that notice, Redmond said he hadn't heard of the public folders restriction for the server product.

Microsoft issued the release-to-manufacturing version of Exchange Server 2013 back in October of 2012, so it's had about a year-and-a-half's worth of time to give fair warning to organizations. The public folder limits for Exchange Online are the same as those for Exchange Server 2013, according to Redmond.

Unnamed sources at Microsoft told Redmond that "the development team are [sic] well aware that these limitations will pose problems for enterprise customers who want to move to either Exchange 2013 on-premises or Exchange Online," according to Redmond's first blog post. Supposedly, the team is "working on the problem."

Good tools to track and delete public folders aren't available and organizations could face going through a manual "pruning" process, which can delay Exchange migrations, Redmond said. He added that organizations could write custom PowerShell scripts to identify candidates for pruning, but they still face uncertainty in determining the value of the information stored in the public folders.

"The PowerShell scripts that are in the public domain are simple, so the reports that they generate are not filtered and do not focus on the need to clean," Redmond explained in his second blog post.

Redmond suggested IT pros bring up why Microsoft failed to communicate the public folder limitations at the company's upcoming Exchange Conference. That conference kicks off at the end of March.

This article originally appeared on, a sister site to GCN.

About the Author

Kurt Mackie is the online news editor for the 1105 Enterprise Computing Group sites, including, and

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