It looks good to me:

 

MX record about fmtechnologies.com exists.
Connection succeeded to mxin.name-services.com SMTP.
220 c2mailgw60.amadis.com ESMTP Postfix

> HELO verify-email.org
250 c2mailgw60.amadis.com

> MAIL FROM: <check@verify-email.org>
=250 2.1.0 Ok

> RCPT TO: <info@fmtechnologies.com>
=250 2.1.5 Ok

5.4.4 is FAILURE TO ROUTE - it's a PERMANENT ERROR and will fail delivery.

 

The recipient's MX server may have had DNS issues at the time and could not be found.

 

See: E-Mail Delivery Error Codes to learn more about non-delivery.

I got this when sending using SmarterMail but using Yahoo Mail, it's delivered successfully and even got a response from the recipient. What could be the issue?

 

 

Original-Recipient: rfc822Failed Recipient: zheng.he@abx.de
Final-Recipient: rfc822Failed Recipient: zheng.he@abx.de
Action: failed
Status: 5.1.1
Diagnostic-Code: smtpCould not deliver message to the following recipient(s):
 
 Failed Recipient: zheng.he@abx.de
 Reason: Remote host said: 550 Requested action not taken: mailbox unavailable
 invalid DNS MX or A/AAAA resource record