I have read the Outlook 2007+ supports borders aside from on images. However, I noticed when using CSS borders on an <a> tag for a button, Outlook 2007 collapses the borders making them smaller, so the button looks like it has less spacing around the button text. The button looks okay (better than using padding), but I have't found anything online about this.
I have also noticed if you apply CSS borders to a TD, Outlook 2007+ also makes the borders smaller if it is above a certain width (1px is fine, but say if it's 10px it will be shrunk down).
Has anyone else run into this issue and does anyone know if there is a solution? It would be great if this could work, especially for buttons, because it wouldn't require the use of the VML solution for buttons for Outlook 2007+.
I've run into the same issue myself unfortunately – borders on elements like links and <div>s (not sure about tables off the top of my head) are limited to a width of 8px according to my testing. This might vary based on the particular circumstances though.
I might add that I tried workarounds like mso-border-alt, to no avail.
Yeah! They get limited to 8px as well for me. It is very odd because from what I have read it should support borders, but as far as I'm concerned this isn't really full support. I'm surprised this hasn't been documented anywhere. I hope to try some testing for workarounds as well.