Connection via tracepath but not via telnet

EDIT:

I have problems sending emails with Thunderbird. IMAP connection works without problems, but SMTP is not connecting. I have tried different settings:

No connection security (port 25), STARTTLS (port 587), but none is connecting to the server.

When I try to connect via telnet I get a timeout: telnet smtp.develman.de 25 resp. telnet smtp.develman.de 587

I have tried to connect via telnet with an online service and the connection was successfull: http://www.adminkit.net/telnet.aspx

Now I have installed wireshark to log the TCP traffic. I do not get any TCP SYN-ACK, only a TCP Retransmission.

I do not know, where the problem is. I also tried to disable clam av but without any success. My system is Archlinux.

Georg Leber

Posted 2013-12-30T17:49:40.560

Reputation: 101

No-one is going to be able to tell you. You've obscured the domain names involved, told us nothing about what "every try" means (not even what software is involved), told us nothing about whether this is a problem you are seeing in a MTA or an MTS, and shown us none of the actual error messages. You'll get random guesses based upon erroneous assumptions, at best. – JdeBP – 2013-12-30T19:17:36.463

Answers

I found the solution:
My router was blocking all smtp-server except smtp-servers configured as permitted servers in the router settings. I have added my smtp-server to the list and now it works.

Georg Leber

Posted 2013-12-30T17:49:40.560

Reputation: 101

Strange question from a fellow Archer...

It appears the site you mention is not accepting telnet connections. You may easily confirm that with nmap, or even with sites like http://ismyportopen.com/. You may do the same with e-mail ports, which you can find here. If the ports are closed, it becomes obvious why you can reach the site, but it does not act upon your requests.

MariusMatutiae

Posted 2013-12-30T17:49:40.560

Reputation: 41 321

Thanks for the hints. The ports are open. I am using the service with my smartphone without problems and I have tried to connect via telnet with the mentioned online telnet service, which also connected successfully. Only the connection via thunderbird is not successfull. – Georg Leber – 2013-12-31T12:30:21.207