Mime Message size is increasing after adding multipart file attachment Spring boot Java

I'm trying to send a mail with attachments. My SMTP server will allow maximum mail size of 10MB. When i'm trying to upload a 10MB file from the front end, the mime message is increasing to 14mb drastically.Is there any way to send without increasing the size. Currently using mutlipart as content type File file = new File(pathToAttachment); message.addAttachment(file.getName(), file);