Email Signature Manager version 5.x
Email Signature Manager version 6.x
Email Signature Manager version 7.x
In certain circumstances, for example when Windows font size is configured as 125% or 150% on high resolution displays, Outlook and OWA resize images if the image size if not specified in the HTML signature.
Email Signature Manager 7.2.0 and later automatically sets the image size in the HTML signature.
If you are using an earlier version, either upgrade, or manually set the image size in the HTML signature.
For information about how to manually set image sizes in HTML signatures, please see the relevant article in the Signature Design section.
Note that when the image size is set, the image will appear smaller when composing email, because it is not scaled to 125% or 150%, but it will appear in the correct size when the email is received. This is due to design of Outlook and OWA.