I know this is probably a simple fix somewhere in my sendmail configuration.

We have a number of employees who are salesmen in the field and use our email server. Simple enough. I am replacing a very old and outdated machine with a new linux box.

RHEL3
sendmail 8.1x

I have everything nearly ready, but when I went to use email from outside of our network, I received an error. I don't recall all the specifics, but something about a 471 error and that the server couldn't relay from my external IP address.

I know there are probably a couple of lines missing from my configuration of sendmail which would allow this, but I also want to try to prevent opening myself up from spammers using my domain... Any advice here would be helpful.

Thanks!

Email servers should be configured as yours is. You don't want everyone in the world to be able to send email through your server, that is how spam is sent.

The best way to do this is to use authentication when sending. Not sure how sendmail is configured on RHEL3, but it may already be setup for this.

Then on the client you change their sending options to authenticate before sending.

There are plain text or encrypted ways of doing this.

I use SASL

I've got SASL installed, but I am trying to find now how I can run sendmail without recompiling (reinstalling?). I am very nervous about blowing away my current configuration because it works. I found a couple of excellent threads here on the boards, but all of them seem more like a starter concept. I am interested in adding SASL to my current configuration without killing sendmail.

1) Can I recompile (reinstall) and have my installation remain intact?
2) Is there simply the ability to edit configuration files to get it to work?

1. your main sendmail config files such as aliases, hosts, domain routing etc should remain, but always backup in case.

2. if sendmail was compiled with auth enabled then you may just have to edit the M4 file and recreate your sendmail.cf file. There is a command you can send sendmail to output what options it was compiled with, google it up, i forgot what it is.

Try

sendmail -d0.1 -bv root | grep SASL

It wasn't compiled with AUTH, so I guess I have few options here than to backup and recompile. I'll follow up with my results...