Home > Exchange > Increase Exchange 2010 OWA Signature Field

Increase Exchange 2010 OWA Signature Field

After recently receiving a new signature format this morning I was faced with an issue regarding the length of my signature. Typically you can get around this by using transport rules, however this was not an option based on how the signature format was given to us.
After about 30 minutes of Google searching I came up empty handed with no way to fix the problem. All searching led me to believe that you had to use Transport Rules to accomplish this. Knowing some about web programming, I knew that this had to be simple restriction within the web programming decided to look there.
I opened the ECP page and found the following within the source code the following line:


ID”:”Messaging”,”Sprite”:”MainNavigationSprite Signature32″,”Title”:”Mail”,”Url”:”\/ecp\/Customize\/Messaging.aspx


This shows that the signature form is located within the ecp/customize/messaging.aspx file.
Once in IIS on the CAS servers I right clicked and ‘explored’ the customize within the ecp page. I opened messaging.aspx with notepad and found that it actually calls EMailSignature.ascx as seen below:


Register Src=”~/Customize/EMailSignature.ascx” TagName=”ES” TagPrefix=”ecp”
Register Src=”~/Customize/MessageFormat.ascx” TagName=”MF” TagPrefix=”ecp”
Register Src=”~/Customize/MessageOptions.ascx” TagName=”MO” TagPrefix=”ecp”
Register Src=”~/Customize/ReadReceipts.ascx” TagName=”RR” TagPrefix=”ecp”
Register Src=”~/Customize/ReadingPane.ascx” TagName=”RP” TagPrefix=”ecp”
Register Src=”~/Customize/Conversations.ascx” TagName=”CS” TagPrefix=”ecp”


Within the EMailSignature.ascx file there is an option which sets limitations on the length:


ecp:RichTextEditor ID=”rteSignatureHtml” runat=”server” DataBoundProperty=”SignatureHtml” MaxLength=”4000″ SetRoles=”Set-MailboxMessageConfiguration?SignatureHtml@W:Self”


I changed the 4000 option to be 12000. Once this was changed and the settings page was reloaded I was then able to change my signature to the new format. Thankfully this change did not require a restart of the website, so there was no outage.


I am working on a powershell script now that will make these changes automatically after Exchange updates so we don’t have to remember to change them back if the field is modified.

  1. John Peterson
    February 18, 2013 at 9:15 am

    Just wanted to leave a note thanking you for documenting this issue.

    • February 18, 2013 at 12:00 pm

      I’m glad this could be of some help. I know it sure bothered me that it was undocumented.

  2. Tamer Hossien
    September 18, 2013 at 10:51 am

    Thank you for this useful tip.

  3. Armin Sparr
    September 30, 2014 at 5:50 am

    You save my day. Thanks a lot. Armin

    • September 30, 2014 at 11:44 am

      Glad I could help! I have a lot more scripts to upload just no time right now. Glad these are still helping people 🙂

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