Hi @Ankush Jassal ,
Outlook 2016 uses Word as a rendering engine, which is different from other web-based email clients. So, it could happen that html emails that can display properly in other email clients may have formatting issues in Outlook desktop clients.
Below are some links about similar situations, you can go through them and make some adjustment in your button code accordingly:
- HTML email link in button not working in outlook desktop
- Display CSS button in Outlook
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