How to set maximum message size to 4MB (4096KB), then use telnet to verify setting.
Check gmail limit size
telnet smtp.gmail.com 25
EHLO practice
You can replace 'practice' with any hostname.
250-SIZE 35883577 means the maximum message size is 35883577 bytes.
In reality, when creating an empty message in gmail and attach an exact 25MBytes (26214400Bytes) file, then send out. The generated message size is up to 35876118Bytes (~34.214MBytes).
