I can not send to outlook.com, can anyone help please? They do not bounce back, the email address is active with a ping test. Thank you in advance.
If you cannot send to an @outlook.com address and doesn’t bounce back and shows in your sent items folder ok, then could be it’s going into the spam / junk folder at the receiving end.
Or there might be a rule setup at the receiving mailbox end moving it to another folder.
So If not in the spam / junk folder at the receiving end or any other mailbox folder at the other end, then I would contact your sending mail server technical support to troubleshoot that for you.