Windows Live won’t send

Can receive but not send mail - just started today.

Windows 10.

Error msg:

unknown error has occurred

Subject'test67'

Server Error: 421

Server Response:421.4.7.1 - connection refused <75.185.128.86> - Too many

concurrent connections (<11>) from source IP

Server.'smtp-server.neo.rr.com'

Windows Live Mail Error ID" 0x800CCC67

Protocol:SMTP

port: 25

Secure(SSL): No