What SMTP port should be used? Port 25 or 587?

What SMTP port should be used? Port 25 or 587? port slot RoundPVC ports are simple enough to add, but what about slot ports? In this video I show how port slot 6 Slot Port

port slot A port is the plug to which you can attach an external device like a printer, external hard drive, or even an external GPU

portal slot 190L volume 500cm2 port cross section and 25cm port length gives a tuning of about 40Hz and port speed of about 40ms So it needs to be flared Part 2 video comparing slot port vs aero port subwoofer boxes In this video we are close to