On Fri, Apr 08, 2005 at 03:41:03AM -0500, Chien-Yu Chen wrote: | I been puzzled by this weird question. I can receive mail on a | debian server, but can't send out mail (connection time out). | | so I do a tcpdump port 25 while doing | telnet mail.math.uiuc.edu 25, result is | | ------------------------ | 21:30:12.426915 192.168.1.102.55486 > mail1.math.uiuc.edu.smtp: S | 2965881252:2965881252(0) win 5840 <mss 1460,sackOK,timestamp 666714841 | 0,nop,wscale 0> (DF) [tos 0x10] | 21:30:15.424652 192.168.1.102.55486 > mail1.math.uiuc.edu.smtp: S | 2965881252:2965881252(0) win 5840 <mss 1460,sackOK,timestamp 666715141 | 0,nop,wscale 0> (DF) [tos 0x10]
Doing a telnet test like that is good, but mail is a bit special, as telnet uses the `A' DNS records, but mail uses the `MX' records. % host -t MX mail.math.uiuc.edu mail.math.uiuc.edu is an alias for mail1.math.uiuc.edu. mail1.math.uiuc.edu mail is handled by 0 mail1.math.uiuc.edu. % host mail.math.uiuc.edu mail.math.uiuc.edu is an alias for mail1.math.uiuc.edu. mail1.math.uiuc.edu has address 130.126.108.26 in this case, the difference does not matter, but in other cases it does. Your tcpdump suggests that nothing is coming back. Your telnet should say -- % telnet mail1.math.uiuc.edu 25 Trying 130.126.108.26... Connected to mail1.math.uiuc.edu. Escape character is '^]'. 220 mail1.math.uiuc.edu ESMTP Sendmail 8.12.10/8.12.10; Mon, 11 Apr 2005 11:26:11 -0500 and I assume it does not. If your system isn't firewalling the connection, then perhaps some other system is. Can you reach other SMTP servers? Many ISPs filter outgoing 25/tcp connections to stop spam. Instead, they force you to relay through their mail server which allows them to throttle the rate at which you can send mail, limiting your ability to spam. It may be that you just need to set your MTA to use the ISP's mail server as a smart relay. -- Doug McLaren, [EMAIL PROTECTED] Those who live by the sword die by the arrow. _______________________________________________ Siglinux mailing list Siglinux@utacm.org http://www.utacm.org:81/mailman/listinfo/siglinux
