Perform a TELNET / TRACEROUTE command

This guide presents commands that can be executed for the purpose of testing a connection or network and thus further specifying the possible source of error.

Performing a Telnet...

TELNET allows you to test the connection to a server without taking into account any additional settings of an email or FTP application to determine the origin of a problem. If the connection does not pass on a SMTP server, you will need to see, for example, if your firewall does not block port 587 or 465.

... on macOS

1. Search Network utility.
2. Go under the Ping, Lookup or Traceroute tab depending on what you want to test.
3. You can also use Terminal and in the window that opens, depending on what you want to test, type:
   traceroute [serveur] 
nc [serveur] [port] 
   Replace [server] with the server name or IP address, idem for [port]...

... on Windows

Enable Telnet in advance if necessary.

1. Open Run and type cmd.
2. In the window that opens, depending on what you want to test, type:
   tracert [serveur] 
telnet [serveur] [port] 
   Example: telnet mail.infomaniak.com 587 (allows you to test the SMTP port if your email software/client does not allow the sending of email)...

... on Android

1. Use the application Simple Telnet Client which allows you to test very simply via 2 fields to fill in (e.g. mail.infomaniak.com and port 143 or 993)…

Perform a PING

PING allows to know whether a machine is accessible via the Internet. You can also check with this tool if you address yourself to the right machine, when changing DNS e.g., by looking at the IP address obtained. It is possible to ping on a domain name, hostname or IP address.