I'm creating a HTML email Signature for a client..

My first version was created using full sized images and style="width: X" in the HTML code, which worked great on my Mac.. However, Outlook didn't like this and the images showed up at full size.

My second version was made using images that I created at the right size. i.e. Twitter logo that I created in AI was 25px X 25px. The images all show up perfectly on Outlook.. However, the quality then doesn't look great.

Can someone suggest how I can make an image small, but the quality high? I've tried amending the DPI, but that makes the image size larger again..

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    FYI likeable.co.nz/… <-- I fully agree with this article. I use plain text email any HTML is always spam.. that pretty logo never gets seen as anything but an annoying, repeated attachment with each and every email I receive.
    – Scott
    Commented May 17, 2018 at 8:47
  • @Scott Although I also agree with that, I think EmmaJ could use some info on exporting images for emails as there is a wider use for them than the specifically mentioned email signatures. I think others could benefit from this question as well :)
    – Summer
    Commented May 17, 2018 at 8:49
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    @JaneDoe1337 troubleshooting Outlook is like trying to get IE6 to understand modern web design.. it's a fools errand in my opinion :) At some point one needs to accept that the tool itself is so outdated and limited that it simply can't handle that whiz-bang thing you want to do.
    – Scott
    Commented May 17, 2018 at 8:50
  • @Scott I feel like you're sort of missing the essence of the question though, outlook is not the root of the issue here. The user mentions DPI as a possible solution for the problem. Loading full sized images is also a bad idea as I pointed out in my answer.
    – Summer
    Commented May 17, 2018 at 8:54
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    @LaurenIpsum I think I'm failing to make my point as I do not disagree with Scott at all. I'm trying to say that OP lacks some basic information that could be valuable for tons of things other than email signatures. Happy to discuss further in chat tho :)
    – Summer
    Commented May 17, 2018 at 11:10

1 Answer 1


In email marketing or just emails in general you do not want full sized images, ever. Even if it would get through spam filters (which are all very trigger happy on image heavy mails), people open these things on their phones, with mobile data etc which can be very annoying for the user.

DPI is used in print only, it doesn't matter with screen graphics. Only the amount of pixels matters. In AI, make sure you use the 'export for screens' functionality. You can change the scale of your image there in case you need to export multiple scales or designed larger than what you need to export. More info on that you can find here.

As to what file extension to use, I think this is a great source that lists the pros and cons of each file type.

  • Thank you - that's a really helpful answer! I will try exporting for screens. I have managed to get the vector images the right size, but they also majorly lost quality when I made them smaller. Am I right in thinking that if I use the large images but scale them down that the quality will be better? Thanks so much!
    – EmmaJ
    Commented May 18, 2018 at 9:09

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