spoofing email

is there a wya to stop ppl from telneting and faking an email from port 25?

What is faking an email or spoofing email?

using the smtp protocol...

mail from: xyz@aol.com
rcpt to: president@whitehouse.gov
data
this is the mail
.

.====================

Running an Open Relay smtp server is the correct term. To fix it simply do not allow relay to IPs you don't recognize as local and domain(s) you don't accept mails for.

but if we block ip's that are not local, then how do we get incoming mail?currently all our mail is comign thriu port 25 of the mail server!

Mail relaying is all about RCPT TO. Your SMTP server should still be wild open for everyone to connect, be it relaying to a remote host or deliverying messages your SMTP (being the MX for abc.com) accepts messages for.
When anyone RCPT TO 123@abc.com your SMTP should then accept it - THIS IS NOT Open Relay.
When someone with a src IP of 192.168.0.5 trying to RCPT TO 456@hotmail.com, your SMTP obviously is not the MX for hotmail.com, therefore, you should reject this. However, when selective relaying is properly configured, and whoever coming from 192.168.0.5 should be a trusted person, you can then configure your SMTP to allow it to deliver to any envelope recipient. Whatever envelope sender he uses make no difference.

If your mail.abc.com is the MX for abc.com domain, you are supposed to ACCEPT anything@abc.com. That said, when someone uses a non-abc.com recipient address and his src IP is not known, you should reject relaying, not port 25 connection.