Microsoft Exchange 2013: OWA Signature Error

In Microsoft Exchange, you may have received these error messages:

  • “The signature is too big. Please try a smaller format.”
  • “The Property X is out of range, the valid range is x to x.”
  • “The length of the property is too long. The maximum length is 8000 and the length of the value provided is 16814.”

I recently encountered these errors with the following setup:

Environment: Exchange 2013 SP3 CU11

Affected User: A tenant in O365 and was migrated back on-premise to an Exchange 2013 server.

Client: Outlook Web Access and Outlook 2010/2013

The Issue

User cannot modify or delete their email signature in Outlook or Outlook Web Access even if you clear the error. User had pasted a large picture into their signature which was acceptable in O365, however it was outside the limits for Exchange 2013.

Also, one of the property settings was outside the acceptable range, causing the second error. The picture is stored as a base64 string that translated to a character length larger than the limit of 8000 characters in an Exchange 2013 signature.

OWA gives the best error message in the picture below:

OWA Error


Relevant Info

Looking at the user’s information in the EAC or AdsiEdit reveals no usable information. You have to do a Get-MailboxMessageConfiguration -Identity user. Upon doing so, you get a large listing of their Outlook configuration (shown in the attached TXT doc at the bottom of this post).

Notice in this example the SignatureHTML is full of the Base64 code. Also notice that DefaultFontSize is set to 11, when the acceptable range is 1-7.


Command –

Set-MailboxMessageConfiguration -Identity user -SignatureText $null -DefaultFontSize 7

This command sets the Signature Text (and also the HTML since it falls under) to null/blank and then sets the DefaultFontSize within an acceptable range. Upon doing so you can click out of the Signature tab and back in to regain access.

File attachments: