css - Email signature hell--How to include a logo image and have it stay sharp?

I found a couple useful threads on this forum with respect to the issues posed by (displaying) images in email signatures-- here, for example-- and I've searched all over the web, but still have not found a good solution that sufficiently addresses the problem. A client of mine would simply like his company's logo included in the signature of his emails, and the issues I've encountered can be summarized as follows:

1. I can export a rasterized version of the logo from AI at actual size, and it will look sharp on the desktop but pixelated/blurry on hi-density (e.g. "retina") displays such as the iPhone.


2. As suggested in the thread I referenced, I can export the logo at 2-3 times the actual, displayed size to target the hi-density displays, but the logo will then look soft on non-hi-density displays when it is scaled down. This is a particular problem in this instance as the logo contains text, which looks terrible when juxtaposed with actual text in the browser/email client.


3. I've considered .svg as an option, but apparently the support is not great; and in this case I'm assuming the vast majority of the users reading this client's email will be using Outlook, so something that only renders properly in iOS/webkit/etc is not a viable option.

I'm at a loss at this point and wondering if there is any other possible option out there. I'm not sure, for instance, if it's possible to implement a hi-density image with lo-res fallback in an email signature?

Any suggestions/insights here are much appreciated. It's bordering on comical how difficult this task has turned out to be.