You are going to have to modify the file "/etc/mail/sendmail.mc" and either change or add some features. Then you will have to make the new sendmail.cf and install it.
The following lines will have to changed or added to sendmail.mc:
FEATURE(masquerade_envelope)dnl
FEATURE(masquerade_entire_domain)dnl
MASQUERADE_DOMAIN(comcast.net)dnl
My ISP is comcast so I send mail to their mail forwarders, otherwise if I send mail from my home IP number it will be considered as spam because most comcast.net IP numbers are MX blacklisted. Only comcast's mail forwarders are removed from the black list.
Probably the most important line is:
define(`SMART_HOST',`smtp.comcast.net')dnl
Sendmail knows to send mail to comcasts mail forwarder before anything else happens.
I also wouldn't be surprised if most ISPs block port 25 so that email can't get out of their domain.
Go to "sendmail.org" and RTFM. You will find what you want there. You will also have to install the sendmail development package (at least on Fedora). Also the m4 assembler will have to be installed so that the sendmail.mc can be compiled into sendmail.cf.
The following lines will have to changed or added to sendmail.mc:
FEATURE(masquerade_envelope)dnl
FEATURE(masquerade_entire_domain)dnl
MASQUERADE_DOMAIN(comcast.net)dnl
My ISP is comcast so I send mail to their mail forwarders, otherwise if I send mail from my home IP number it will be considered as spam because most comcast.net IP numbers are MX blacklisted. Only comcast's mail forwarders are removed from the black list.
Probably the most important line is:
define(`SMART_HOST',`smtp.comcast.net')dnl
Sendmail knows to send mail to comcasts mail forwarder before anything else happens.
I also wouldn't be surprised if most ISPs block port 25 so that email can't get out of their domain.
Go to "sendmail.org" and RTFM. You will find what you want there. You will also have to install the sendmail development package (at least on Fedora). Also the m4 assembler will have to be installed so that the sendmail.mc can be compiled into sendmail.cf.