How to avoid problems with SVG images in email signatures

Problem:

You are trying to use SVG images in email signatures. Unfortunately, you are unable to insert such signatures (either automatically or manually) into emails by using the CodeTwo Signatures Web Add-in in Outlook on the web (OWA). Instead, you receive the following error:

Your signature could not be inserted.

What’s more, you notice that emails with SVG images are very often treated as spam.

Solution:

The problem with pictures in the SVG format is that they can be potentially harmful – attackers can easily exploit them to embed malicious JavaScript code. That’s why Outlook on the web might apply certain security policies that block SVG content, thus blocking the insertion of the affected signature as well. The fact that emails with SVG content are often classified as spam by email servers also goes in line with the assumption that the format might be generally unsafe to use.

Tips for replacing an SVG picture in an email signature

If you want to use SVG content in your email signatures to take advantage of SVG’s scalability without loss of quality (sharpness), you might consider an alternative approach: using raster graphics (in the PNG or JPG format) of doubled size.

For example, if you have a company logo in the SVG format, you need to convert it to PNG or JPG and make sure that it meets the following characteristics:

• The image size should be twice as big as the default size you want to use in your signature. For example, if you want the logo to display in 150x150 pixels, your image dimensions should be 300x300 pixels. That way, the logo will be easily scalable and sharp on high-resolution screens like 4k screens, Retina displays, etc.
• The image’s width and length values should be even. 300x300 pixels is OK, as it gives 150x150 pixels when divided by 2. That way scaling will be performed without any quality loss issues.

Once your logo has been prepared according to the above guidelines, insert it to your email signature, following these instructions. By default, the original size values (e.g. 300x300 pixels) will be shown in Width and Height fields. Remember to change them to the values that are twice smaller, e.g. 150x150 pixels (Fig. 1.). These will be the default values that will apply to standard HD screens. For 4k screens, the logo will be displayed in its full size instead, preserving its quality.

Fig. 1. Changing the original image size (for 4k screens) to the size displayed by default (for HD screens).

See also:

• Images in email signatures – linked or embedded?
• Good practices for preparing an email signature