Hello everybody. In the company I work we got a problem with our email system, we can receive emails from hotmail, yahoo, gmail or any external site but we can send to anywhere and receive internal mail.  We have an exchange server, an isa server, and we manage our dns servers. the problem began when our ISP change our public IP we did the changes but now he have been in problems with the mails for more than two months. Any ideas?????

Please restate the issue. I'm not clear on what you are experiencing.

I suspect you are stating that inbound mail from the internet is not coming in correctly.

This is likely due to bad MX records on your external DNS entries.

on a machine connected to the internet running 2k/xp/2k3 open a command prompt,

type "nslookup" and press enter <enter>

type "server <isp dns server ip>  < enter>    example: "server 101.111.222.222" <enter>

type "set type=mx" <enter>

type "youremaildomain.com" <enter>   example: if your email address is janedoe@mycompany.com then you would type "mycompany.com" <enter>  (remember <enter> means hit the enter key)

you should get a list of your mx records like this

mx 10 mailservername.mycompany.com

mx 20 mailservername2.mycompany.com

 note what it says for the mailservernames for your domain,

type "set type=A" <enter>

type "mailservername.mycompany.com" <enter>    verify the IP address returned is your correct external IP as changed by your ISP.

 repeat for all entries and verify they refer to the correct resources as expected.

Hope this helps.

Jerry