Dear Sir/Madam,

Recently we have been receiving these emails? Can you please advise why and how to fix?

This message was created automatically by mail delivery system.

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

The original message was received at Mon, 21 May 2018 01:46:46 -0700  from   david.tsai@konmax.com[ david.tsai@konmax.com]  

    ----- The following addresses had fatal errors -----    

   [Status: Error, Address: < jessica.wang@konmax.com.cn>, ResponseCode 421, Problem communicating with the recipient server, Status: Error, Address: < xuelian.miao@konmax.com.cn>, ResponseCode 421, Problem communicating with the recipient server]

Message will be retried for 4 more day(s)