This can be caused by copying and pasting in text from a Word document or other source into the pop up email template.
The action of copying and pasting will bring across different formats of font style and size and this can mean that if you have altered the text inside the template (using the editing tools) the text can still carry the previous formatting styles and so look different when it is actually sent.
You may need to alter the HTML code of the font style and text size by accessing this via the Source Code icon as shown below:
From inside the source code you can see the font style and the font size as shown below:
Make your changes to the font size and font style and click on OK to save.
If you have any questions please contact our Support Helpdesk.