Buttondown, which powers The Newsletter Leaf Journal, published an informative post explaining how some email hosts clip emails that reach a certain size. It varies based on email provider.

Several email apps, like Outlook, Apple Mail, and Proton, won’t constrain your emails beyond the limits set by SMTP. Others do, though. Gmail cuts a received email short once it hits 102kb in size (not counting attachments). That tends to work out to around 17,000 words of plain text, or as low as 7,000 words when there’s a reasonable amount of formatting.

For newsletters, clipping can affect deliverability if the unsubscribe link (usually included in the footer) is clipped. While many of my issues of The Newsletter Leaf Journal fall in the 2,000-3,000 word range, I am happy to learn that I have never come close to hitting Gmail’s (or likely any email host’s) size limits.