How to fix message is too large for the receiving server
Mail-List.com will accept attachments up to 25 megabytes in size, and send those same files out to all subscribers.
However, not all ISP's will accept big files, and many times attachments get caught by the spam filters at your subscriber's ISP.
Increasing the size of the emails we accept, can cause bigger problems.
Because if any of your subscribers can not accept very large emails, then those emails will not be delivered.
Gmail accepts messages up to 25 megabytes.
Note that encoding the file increases the size of the attachment
Technically, email is limited to ASCII text, so binary files must be encoded to prevent data corruption.
Base64 is typically used for encoding, however it increases the size of the file substantially.
Put the file in Cloud Storage
Dropbox, Google Drive, OneDrive
Then put the URL of the very large file in the email.
Or use a large file Sending Service