remote mail server rejects connection after 2 hours

jfish

This is new to me, symptoms is using Outlook 2019 to connect to mail server (doesnt matter if connecting with POP3 or IMAP).

New build of pfsense running 2.5.1.

I can connect and send and recieve emails., now aafter 2 hours connection is rejected

This i is output from pfsense

pfTop: Up State 1-4/4 (443), View: default, Order: dest. addr
PR DIR SRC DEST STATE AGE EXP PKTS BYTES
tcp In 192.168.x.y:55083 aaa.bb.cc.dd:143 CLOSED:SYN_SENT 00:00:44 00:00:01 5 260
tcp Out aaa.bb.cc.dd:57975 aaa.bb.cc.dd:143 SYN_SENT:CLOSED 00:00:44 00:00:01 5 260
tcp In 192.168.16.172:55130 aaa.bb.cc.dd:143 CLOSED:SYN_SENT 00:00:02 00:00:29 2 104
tcp Out aaa.bb.cc.dd:14256 aaa.bb.cc.dd:143 SYN_SENT:CLOSED 00:00:02 00:00:29 2 104

Is issue with remote server, is it rejecting my connections. Rather baffled by this

Gertjan

@jfish said in remote mail server rejects connection after 2 hours:

tcp In 192.168.x.y:55083 aaa.bb.cc.dd:143 CLOSED:SYN_SENT 00:00:44 00:00:01 5 260

Your mail client starts a CLOSED:SYN_SENT sequence request - to end a "IMAP=port 143" connection.
The server confirms the request.

At any time the connection could be build up again, at the request of the client.
The server should accept it, of course (login credentials etc)

jfish

@gertjan the issue is the remote mail server was accepting connections and thus I was able to send and receive emails, after 2 hours the remote server is now not accepting connections.

No changes done on the pfsense firewall for this to occur

The issue occurs with any of the mail protocols be it IMAP, POP3 SMTP be is TLS or non TLS

Has the remote host black listed my external IP address now

Gertjan

@jfish said in remote mail server rejects connection after 2 hours:

Has the remote host black listed my external IP address now

Is that a question or a fact ?
Check with them ?

Packet capture the traffic to them, using their IP, TCP, and the ports 110 143 or whatever you use.
If you set Outlook to sync with mail servers every minute or so, then yes, you would get blacklisted everywhere ^^