When test viewing our campaign http://email.targetemail.ca/T/ViewEmail/r/747CF63E3DC6952A in IE, the main table is too wide, however in FireFox it is fine.
Another strange thing is that when I send a test email to my Outlook Express client, it renders fine upon the first open. If I open it a second time, the width is then again too wide.
Any suggestions are greatly appreciated.
I understand you posted this 4 days ago, so sorry if this help is too late.
I had a similar problem when I started producing some new email templates after a long break, where in the meantime I had been developing sites. Since the two are quite different in what works, and what doesn't, I fell to a couple of simple mistakes.
One of these had the effect you've described. You may have used "XXpx" for height/width of HTML-styled elements. (e.g. <table width="600px"></table>) This does not render correctly; you should omit the "px."
<table id="container" width="600" cellspacing="0" cellpadding="0" border="0"> <tr> <td> </td> </tr> </table>
<table id="container" width="600px" cellspacing="0" cellpadding="0" border="0"> <tr> <td> </td> </tr> </table>
Hope that helps!