Great comments Jake, and that’s a very good point about older versions of Outlook using IE6 for the rendering engine (like Outlook 2000), so if you see a percentage f them in your list perhaps 24-bit PNG’s should be avoided altogether.
Nice reminder. Was developing a new newsletter, using the PNG format, and got your tweet. Perfect timing.
Even PNG-8 with Transparency is pretty well supported – it uses one colour as the transparency just like GIF does, and often yields better quality.
Be careful with PNG-24 with Alpha Transparency. If you’re sending out to a lot of businesses with Outlook then it’s likely they’ll not only be using a pre-Outlook 2007 but probably Internet Explorer 6. The problem here is that anything below Outlook 2007 will use the Internet Explorer render engine (which ever version you have on your PC) and because IE6 has NO support for Alpha Transparency at all, you’re going to find that some very odd things start happening when it displays in your emails.
My advice would still be to try and avoid alpha transparency with PNG as much as possible.
Thats very useful Jake. Thanks.
Having worked with CSS issues (and issues and issues ..) with IE 6 i can say that it DOES support alpha transparency for PNGs. But you will need to enable the PNG Active X control. Something like so :
24 bit PNGs are supported too.
My advices after my background, would be the following ones :
– PNG, GIF, JPEG are standards compatible with 100% browsers; still, avoid if possible transparent ones that does not fit fit into this category, and for old-school clients like Internet Explorer, don’t use png (this high-end format is still too new for MS$ after 4 years of GPL :p)