Gmail will cut off and display [Message clipped] View entire message at the bottom of your email if the email is larger than 102kb.
This limit can be reached if there is a large amount of content (this includes formatting code and images) in your email. You may also see this happen after sending yourself multiple test emails with the same subject line because they will appear as part of a conversation thread in your inbox and later messages will be clipped.
To avoid this, it may be best to revise and reduce the amount of content in your email. Review our article on HubSpot email tool best practices for some guidance.
Please note: the 102kb limit is based on the amount of content in the HTML code, not the size of specific images in your message. While resizing an image will not change the size of the content, deleting an image from the email body will reduce the size of the message.