A client who was changing their email signatures wanted to standardise on the same sigs for Outlook based and OWA users. Then OWA started to complain that the signature was too big. On checking I realised that the default 2007 limit is quite small 4K but that with a registry change it could be increased to 16 K
The default SignatureMaxLength value is 4096 (4KB) and the maximum value is 16672 (16KB).
so you need to add to the registry
SignatureMaxLength – DWORD and set value to 4120 in Hex or 16672 in decimal
or save the lines below to a .reg file on the server in question and import that way
Windows Registry Editor Version 5.00