Exim Block IP from connecting to port 25

[gutizz]

Recently one server of mine failed to connect to port 25 of another, both are using cpanel exim. I tried to telnet to port 25 without success, the connection drops after connected.

Trying xxx.xx.xxx.xx...
Connected to myhost.com (xxx.xx.xxx.xx).
Escape character is '^]'.
Connection closed by foreign host.

While checking tcpdump, the connection reset by the host.

15:11:52.633973 IP ww.www.ww.www.29395 > xxx.xx.xxx.xx.25: S 1550485901:1550485901 win 5840
15:11:52.634410 IP xxx.xx.xxx.xx.25 > ww.www.ww.www.29395: S 1945331713:1945331713 ack 1550485902 win 5840
15:11:52.634436 IP ww.www.ww.www.29395 > xxx.xx.xxx.xx.25: . ack 1 win 5840
15:11:52.635444 IP xxx.xx.xxx.xx.25 > ww.www.ww.www.29395: R 1945331714:1945331714 win 0

Is there any block can cause this? I have checked exim_deny, rblblacklist. Thanks.

[brianoz]

Is there something in your firewall causing this? Does it work from localhost?

[gutizz]

Hi, if my firewall blocking the ip, no way it can be connected at first place. In this case, seems somewhere in exim rejected my connection.

[gutizz]

Anyone could assist on this issue?

[nisse]

Look in the exim_mainlog of the host that's dropping the connection to see why it's doing it.

[Dale S]

My e-mail has been working fine for over two years and suddenly I couldn't send outbound mail. I could move my computer to another location and it worked fine. After a day of trouble shooting it appears my local ISP (Comcast) is blocking port 25 (even though they claim they are not) Not only were e-mail accounts on my server not working but other accounts were not working. I switched the outgoing so they would go out using a Comcast account on port 465. It works for now. I will need a long term solution. Is there another port that can be used to send outgoing mail and how would I set that up?

[LP-Tim]

In Service Manager you can enable Exim on an additional port, like 26 for example. Lots of ISPs block port 25.

[gutizz]

Hi Dale, it's different case

Well, there is nothing in exim_mainlog other than a connection reset.