What is causing these rejection messages?

Log Name: Application
Source: MSExchangeTransport
Date: 01/12/2020 12:37:38
Event ID: 1021
Task Category: SmtpReceive
Level: Warning
Keywords: Classic
User: N/A
Computer: server-EX1.server.local
Description:
Receive connector mail.server.co.uk rejected an incoming connection from IP address 168.245.1.20. The maximum number of connections per source (20) for this connector has been reached by this source IP address.
Event Xml:



1021
3
1
0x80000000000000

1142871
Application
server-EX1.server.local



mail.server.co.uk
20
168.245.1.20

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We are running AVG email scanner on our Exchange 2007 box btw

And are also seeing this, which is presumably an AVG generated message on EX2007

Log Name: Application
Source: MSExchangeTransport
Date: 01/12/2020 12:23:06
Event ID: 1022
Task Category: SmtpReceive
Level: Warning
Keywords: Classic
User: N/A
Computer: server-EX1.server.local
Description:
Anti-spam agents are enabled, but the list of internal SMTP servers is empty. If there are any MTAs between this server and the Internet, populate this list by using the Set-TransportConfig cmdlet in the Exchange Management Shell.
Event Xml:



1022
3
1
0x80000000000000

1142800
Application
server-EX1.server.local



mail.server.co.uk
5000

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