When sending email ( ex. to hotmail user ) router response is "Error transferring to 62.48.240.57; SMTP Protocol Returned a Permanent Error 554 5.5.2 No valid recipients"The 62.48.240.57 ip is our mx record…
The Error Message is clear. The foreign Host denies your Mail because of the Sender address. The Domino Router reports the Errors according to the RFC-Pages. Look at www.ietf.org → RFC Pages → type in 1893 this page contains the SMTP Error Message Codes
following link will definily help you to resolve the problem. Also please check what spam filterning you enabled nad check the following in the server documents also (Only guess)