If your subscriber list has over 1000 subscribers, then the maximum size of an email you may submit for distribution is 3MB. If you have 500-1000 subscribers, your max message size is 6MB. If your list has fewer than 500 subscribers, there is still a 10MB message size limit.
That includes embedded images, attached files, etc. The reason is in the math: a 3MB message multiplied by 1000 copies sent to subscribers equals 3GB of email! A couple of messages of that size submitted by several customers within a few hours can quickly consume all the available working HDD space on our server.
The solution is simple: reduce the size of your message. Some possibilities:
- If you have embedded an image in the email, remove that and instead insert a LINK to the image, hosted on an image hosting site like Gifyu.
- If you are sending an attachment, reduce its size (which is usually caused by uncompressed embedded images).
- Consider putting the attachment on a website instead and just including a link to it in your newsletter. This has the added advantage of not forcing your recipients to each download an attachment which they may not need or want.