SBS2011 Exchange 2010 mail stuck in smtp queue with " 451 4.4.0 primary target ip address responded with 421 4.2.1 unable to connect" error
Posted on 2012-08-30
After having done a migration from a SBS2003 server to a new SBS2011 server, i'm getting a strange pb, all mail sending from my users are stuck in smtp queue on exchange 2010 whith 451 4.4.0 primary target ip address responded with: 451 4.4.0 primary target ip address responded with 421 4.2.1 unable to connect error".
SBS2011 use a smtp relay with no authentification to relay mail (Internet Provider SMTP relay), the following commands are OK from my server to the smtp relay :
telnet smtp.xxxx.yy 25
mail from: firstname.lastname@example.org
rcpt to: email@example.com
Doing this the mail is sending without pb
I've also test DNS with nslookup with good results.
I've recreate the sending connector on my exchange 2010 ECM with smtp,*,1 and network configure to be smtp.myprovider.com with no authentification.
Networks and Internet SBS assistant have been done correctly.