New Edge server fails with DNS lookups - incoming mail stuck in queue

Question

I just setup an Edge server, together with 2 Ex2013 servers with DAG. Sync works fine, however incoming mails are stuck at the edge server. The queue looks like this:
451 4.4.0 DNS query failed. The error was: DNS query failed with error ErrorRetry
Checking the logs, it also shows errors like this:
2014-07-12T16:32:06.599Z,08D16C05D02E2774,SMTP,"ex2.internal.contoso.com,ex3.internal.contoso.com,ex4.internal.contoso.com",>,DNS server returned ErrorRetry reported by 0.0.0.0. [Domain:Result] = EX2.internal.contoso.com:ErrorRetry; EX3.internal.contoso.com:ErrorRetry; EX4.internal.contoso.com:ErrorRetry;
2014-07-12T16:32:06.599Z,08D16C05D02E2774,SMTP,"ex2.internal.contoso.com,ex3.internal.contoso.com,ex4.internal.contoso.com",-,"Messages: 0 Bytes: 0 (The DNS query for 'SmartHostConnectorDelivery':'ex2.internal.contoso.com,ex3.internal.contoso.com,ex4.internal.contoso.com':'e01d6f93-e25b-4e36-9f2f-c1c7c73889ae' failed with error : ErrorRetry)"
Now the network is a little special, as the edge server is not in DMZ, but simply in a workgroup in the same LAN as the other Exchange servers. The edge server NIC's are configured to use the internal AD DNS servers, and the edge server is able to lookup
all the other exchange servers (ie. ex2.internal.contoso.com).
So I wonder why the edge servers logs DNS lookup errors as long as the server it self can lookup the internal hostnames for Exchange.
Any help would be great, as all incoming mail is now stuck at the edge server.

Answer 1

This is from the Edge server:
[PS] C:\Windows\system32>Get-SendConnector | fl
AddressSpaces                : {smtp:*;100}
AuthenticationCredential     :
CloudServicesMailEnabled     : False
Comment                      :
ConnectedDomains             : {}
ConnectionInactivityTimeOut  : 00:10:00
DNSRoutingEnabled            : True
DomainSecureEnabled          : True
Enabled                      : True
ErrorPolicies                : Default
ForceHELO                    : False
Fqdn                         :
FrontendProxyEnabled         : False
HomeMTA                      :
HomeMtaServerId              :
Identity                     : EdgeSync - MyCity to Internet
IgnoreSTARTTLS               : False
IsScopedConnector            : False
IsSmtpConnector              : True
MaxMessageSize               : 100 MB (104,857,600 bytes)
Name                         : EdgeSync - MyCity to Internet
Port                         : 25
ProtocolLoggingLevel         : Verbose
RequireOorg                  : False
RequireTLS                   : False
SmartHostAuthMechanism       : None
SmartHosts                   : {}
SmartHostsString             :
SmtpMaxMessagesPerConnection : 20
SourceIPAddress              : 0.0.0.0
SourceRoutingGroup           : Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers       : {}
TlsAuthLevel                 :
TlsCertificateName           :
TlsDomain                    :
UseExternalDNSServersEnabled : False
AddressSpaces                : {smtp:--;100}
AuthenticationCredential     :
CloudServicesMailEnabled     : False
Comment                      :
ConnectedDomains             : {}
ConnectionInactivityTimeOut  : 00:10:00
DNSRoutingEnabled            : False
DomainSecureEnabled          : False
Enabled                      : True
ErrorPolicies                : Default
ForceHELO                    : False
Fqdn                         :
FrontendProxyEnabled         : False
HomeMTA                      :
HomeMtaServerId              :
Identity                     : EdgeSync - Inbound to MyCity
IgnoreSTARTTLS               : False
IsScopedConnector            : False
IsSmtpConnector              : True
MaxMessageSize               : Unlimited
Name                         : EdgeSync - Inbound to MyCity
Port                         : 25
ProtocolLoggingLevel         : Verbose
RequireOorg                  : False
RequireTLS                   : False
SmartHostAuthMechanism       : ExchangeServer
SmartHosts                   : {--}
SmartHostsString             : --
SmtpMaxMessagesPerConnection : 20
SourceIPAddress              : 0.0.0.0
SourceRoutingGroup           : Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers       : {}
TlsAuthLevel                 :
TlsCertificateName           :
TlsDomain                    :
UseExternalDNSServersEnabled : False
This is from the Hub/CAS/MBX server:
[PS] C:\Windows\system32>Get-SendConnector | fl
AddressSpaces                : {SMTP:*;1}
AuthenticationCredential     :
CloudServicesMailEnabled     : False
Comment                      :
ConnectedDomains             : {}
ConnectionInactivityTimeOut  : 00:10:00
DNSRoutingEnabled            : True
DomainSecureEnabled          : False
Enabled                      : False
ErrorPolicies                : Default
ForceHELO                    : False
Fqdn                         : mail.va-world.com
FrontendProxyEnabled         : False
HomeMTA                      : Microsoft MTA
HomeMtaServerId              : EX3
Identity                     : outgoing SMTP
IgnoreSTARTTLS               : False
IsScopedConnector            : False
IsSmtpConnector              : True
MaxMessageSize               : 151.6 MB (158,965,760 bytes)
Name                         : outgoing SMTP
Port                         : 25
ProtocolLoggingLevel         : Verbose
RequireOorg                  : False
RequireTLS                   : False
SmartHostAuthMechanism       : None
SmartHosts                   : {}
SmartHostsString             :
SmtpMaxMessagesPerConnection : 20
SourceIPAddress              : 0.0.0.0
SourceRoutingGroup           : Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers       : {EX4, EX3}
TlsAuthLevel                 :
TlsCertificateName           :
TlsDomain                    :
UseExternalDNSServersEnabled : False
AddressSpaces                : {smtp:*;100}
AuthenticationCredential     :
CloudServicesMailEnabled     : False
Comment                      :
ConnectedDomains             : {}
ConnectionInactivityTimeOut  : 00:10:00
DNSRoutingEnabled            : True
DomainSecureEnabled          : True
Enabled                      : True
ErrorPolicies                : Default
ForceHELO                    : False
Fqdn                         :
FrontendProxyEnabled         : False
HomeMTA                      : Microsoft MTA
HomeMtaServerId              : Edge01
Identity                     : EdgeSync - MyCity to Internet
IgnoreSTARTTLS               : False
IsScopedConnector            : False
IsSmtpConnector              : True
MaxMessageSize               : 100 MB (104,857,600 bytes)
Name                         : EdgeSync - MyCity to Internet
Port                         : 25
ProtocolLoggingLevel         : Verbose
RequireOorg                  : False
RequireTLS                   : False
SmartHostAuthMechanism       : None
SmartHosts                   : {}
SmartHostsString             :
SmtpMaxMessagesPerConnection : 20
SourceIPAddress              : 0.0.0.0
SourceRoutingGroup           : Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers       : {Edge01}
TlsAuthLevel                 :
TlsCertificateName           :
TlsDomain                    :
UseExternalDNSServersEnabled : False
AddressSpaces                : {smtp:--;100}
AuthenticationCredential     :
CloudServicesMailEnabled     : False
Comment                      :
ConnectedDomains             : {}
ConnectionInactivityTimeOut  : 00:10:00
DNSRoutingEnabled            : False
DomainSecureEnabled          : False
Enabled                      : True
ErrorPolicies                : Default
ForceHELO                    : False
Fqdn                         :
FrontendProxyEnabled         : False
HomeMTA                      : Microsoft MTA
HomeMtaServerId              : Edge01
Identity                     : EdgeSync - Inbound to MyCity
IgnoreSTARTTLS               : False
IsScopedConnector            : False
IsSmtpConnector              : True
MaxMessageSize               : Unlimited
Name                         : EdgeSync - Inbound to MyCity
Port                         : 25
ProtocolLoggingLevel         : Verbose
RequireOorg                  : False
RequireTLS                   : False
SmartHostAuthMechanism       : ExchangeServer
SmartHosts                   : {--}
SmartHostsString             : --
SmtpMaxMessagesPerConnection : 20
SourceIPAddress              : 0.0.0.0
SourceRoutingGroup           : Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers       : {Edge01}
TlsAuthLevel                 :
TlsCertificateName           :
TlsDomain                    :
UseExternalDNSServersEnabled : False
I should note that all the Exchange servers are behind the same public IP, I just use NAT in my firewall to seperate the ports (50636 and 25 into the Edge server, 80/443 into the CAS/MBS server).