We recently ran into a problem with changing the mail signature of a client that the new signature that he wanted was simply to long for Outlook Web App to handle by default. After a long search on the web we found a great link that helped us with the problem and got it resolved.
However we wanted and needed to do this as a script so that with an Exchange update we could retain the new field size.So with some help I created a simple script that allows you to set the signature field length to whatever you want.
Keep in mind that the default value before you start editing is 4000. This way you can always return to the default if you require it.
The original post that we found that references this issue can be found here.
A download link to a PowerShell script that you can run can be found here.
Feedback is of course always welcome and I will try to implement them. This post is here for people that need help with figuring this whole thing out. The script is very simple to just do the job it is meant to do.