If the attachment is too large, it can only be divided by a file splitter or compressed directly by Winrar. Take the second method as an example: right-click the file to be sent, select "Add to Compressed File", and enter the file size in the "Compressed Volume Size, Bytes (V)" box at the bottom of the General tab of the open window, and then the file will be automatically divided and compressed into multiple files, so that it can be sent. (Just divide the 40M file into four parts. )

Satisfied, please adopt.