Apsona has not yet been updated to fully support Lightning Email Templates. While many customers do use LEX email templates in Apsona without issue, we see occasional issues pop up. If classic email templates are an option, consider using them as you should see more consistently correct behavior from Apsona. See this article for more details.
Here are some things to try:
It may be that the CSS used in the email template is not compliant with the email client that the email was delivered to. For example, Gmail removes CSS from email style tags and sanitizes all HTML content which causes the styles to be stripped out. This is a common behavior in many email clients, particularly Gmail, to enhance security and ensure proper rendering across different platforms.
To resolve this, we recommend converting your email template CSS into inline styles. Inline CSS is less likely to be removed or altered by email clients. You can use online tools like Mailchimp's CSS inliner (https://templates.mailchimp.com/resources/inline-css/) to automate this process. This approach ensures that the styles are preserved, and the email renders as intended across different email clients.
Here is a quick summary of the steps you can follow: