Actually, it might not be just a problem of "reverse name" but more a problem of "coming from a cable connection". However, check with your ISP if you can change the reverse name of your connection (something like "cable.mycompany.tld" is better than "XX-YYY-YYYYY.cablecompany.tld").
Your IP address is in a "cable connection" pool of IP and Yahoo (like others) do not allow direct connection to their SMTP servers from these IP.
You'll have to find a smarthost on the Internet, ie a server that is able to relay your SMTP connection. This way all the mails (for the outside) will leave your Zimbra server for this smarthost then go to the destination server.
Your ISP's SMTP server can usualy be used for this. |