Gmail can clip or hide the full content of your email under the View entire message link if your email content is larger than 102 KB.
This will not affect the open and click rate of your campaign since our tracking pixel is located at the very top of the email.
Some measures you can take to prevent this from happening are:
Don’t use the same subject line - Gmail groups emails with the same subject line together, regardless of the date and email content. This also occurs when you send test emails of the same campaign multiple times, which is why we recommend changing the subject line or deleting the first campaign from your inbox.
Summarize your information - Include the most relevant information in your campaign with links to the full content on your website. This is not only a good tip for this particular issue but also a good tip for general subscriber engagement.
Avoid copying the content from another source - Sometimes copying text from an external source may enlarge the size of the content due to its formatting. If you must copy the content, you can use this external tool to remove any formatting of the text, use the plain-text paste function, or the Rich text editor option.
Minimize your code - This includes removing notes, white spaces, double spaces, line breaks, and tabs. Just keep in mind it should be your last step as the code is difficult to read after removing those elements.