We are seeing the following in our Exchange 2016 server logs:

Log Name: Application
Source: MSExchangeTransport
Date: 12/07/2017 06:09:47
Event ID: 8019
Task Category: RemoteDelivery
Level: Warning
Keywords: Classic
User: N/A
Computer: servername.domain.suffix
Description:
Creating extra connection for idle queue: 18698 with queue type: DnsConnectorDelivery and next hop domain: gigatronic.es. Current number of connections is: 1
Event Xml:



8019
3
7
0x80000000000000

3998306
Application
servername.domain.suffix



18698
DnsConnectorDelivery
gigatronic.es
1

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Just to say that this domain has been refusing our emails occasionally - presumably due to some anti-spam issue.

In this case the DNS servers could not derive an IP address or an MX record and so the email could not be delivered.

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