Script Download:SetOSCEXOEmailSignature.zip
http://gallery.technet.microsoft.com/scriptcenter/Set-Email-Signatures-in-792587f5

This script can set text and HTML email signatures to your outgoing email messages in Office 365 Exchange Online.

​Microsoft Outlook enables you to change email signatures very easily. However, this feature is difficult to use in Outlook Web App (OWA). For example, it may be difficult to insert images as signatures. Therefore, in order to set email signatures in OWA, you must find a workaround.

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You can find more All-In-One Script Framework script samples at http://aka.ms/onescriptingallery