It's possible that your email provider might place a limit on the number of words but I've certainly never heard of any provider doing so. It's more usual to place a limit on the total file size of the email, including any attachments.
Many email services won't accept mail with a size of over, say, 10Mb. It's easy to exceed that size if you're attaching pictures taken with a digital camera but almost impossible with just text. (I've written 22,000 words of a novel and the file size is still only 0.223Mb. Unless you've just typed out 'War and Peace', it's unlikely that your email was too big!)
Chris