Gmail has a limit for email size, which when exceeded causes messages to get clipped:
This limit is 102Kb, and includes the entire message (headers+body), after encoding in Base64 as it will appear for the recipient. The message size is based on the total number of bytes in the email's code. This includes the following items:
- The message body with all of its elements (subject, preheader, text, images, links)
- The HTML code with all link URLs and image URLs
- The links after being wrapped in unique URL for tracking purposes
- The open tracking pixel URL; the unsubscribe link
- The full header of the message with SMTP delivery and authentication information
- Base64 encoding of the message. Each letter or character of the raw code is approximately 1 to 2 bytes. The total byte size of every character in the code creates the raw message size. BASE 64 encodes each set of three bytes into four bytes. In addition, the output is padded to always be a multiple of four. This results in size increase of around 37% after encoding, and the encoding is done after the email is sent.
How to prevent clipping
1. Remove any extra code created when you copy and paste content
When you write your code in an outside word processing program, blog etc. and copy+paste it elsewhere (including Leanplum), you may pick up the HTML along with some extra hidden formatting from the other source. This will inflate your message size - make sure to paste it as plain text.
2. Remove unnecessary content/bloated code
Before you make any changes, we recommend that you copy the campaign. This will leave a backup copy of your campaign with all the original content, just in case important content is accidentally deleted.
3. After you remove some of the content, run Inbox Preview.
Inbox Preview will show you if Gmail still clips your message.
4. To determine the final size of your sent email, send it to a test Gmail/Google Workspace address.
View the header in a browser and not the mobile app (go to “Show original” in Gmail ), and save it in a document. Then view the file size of that document.
NB! If you resize a particularly large image, it does not reduce the size of the message. All email images are loaded from an external source (web server), the image size does not affect the size of the message. Instead of reducing image size, try deleting an unnecessary image - this would remove its associated code.