Plus most id10ts uses outlook express, and to the best of my knowledge outlook sends first then receives . Good luck. Try hacking outlook to change this?

not quite true. If yo open Outlook Express it will check first + send, but when you have it open and create new mail + send it, i t wouldn't do any checking before sending.

btw
I figure out what is causing problem. It's kaspersky antivirus (kavkeeper), because it doesn't let sendmail to reject by rules in access, virtusertable.. first. Instead all mail proceeds to AV checking and then gets rejected, which causes a problem, when no "from" tag is specified.
I'm trying to work that out somehow.

well, good luck. I don't bother with anti virus. I feel every user is there for himself. But then again - that is probably rude and checking for virusses is probably a good thing. But oh well, that is just me.

having antivirus on server saves (I guess not much in my case) you a lot of time=money.
Just think how much time do you need to take care of viruses on corporate network with even 20 computers

true - but then again. All the windows machines in the network has Norton installed. But that is on a local lan, plus I only do relay to outside, mx is hosted somewhere else. But still - it would only be polite .

btw don't trust norton too much, we had it on 2 workstations installed and fully updated, but still very klez.h viruses ?

just blocked one the other night using it. and i don't trust any system running anything from M$ ...

?
what is running from M$

meaning if it runs windows (from M$ - don't trust it). Or any other product for that matter, so in order to run Norton, you need windows AFAIK, so it runs Windows, so I don't trust it.

btw, I tried to figure out if there is any free AV software for linux/sendmail, but no luck. Wierd a? no opens source project to deal with viruses

it would be just a little hard for open source developpers to sink the amount of time required for the above... most devellopers cant realease emergency patches every day... there is a reason you pay a faily high price for norton they have a lot of people working on new viruse defenitions...

detecting viruses isnt the easiest thing to do, due to the huge variety

quote:
...or norton they have a lot of people working on new viruse defenitions...
---------------

I think they have some additional to work on new viruses as well

There's a great set of tools to help block spam, check for virus's and such as that.

Mailscanner - checks for virus's and really weird stuffs, can use several different virus packages
http://www.sng.ecs.soton.ac.uk/mailscanner/

SpamAssassin - set of perl scripts that fit nicely in with MailScanner
http://spamassassin.taint.org/

I also use RBL (blackhole) for keeping out those nasty spamservers.
www.five-ten-sg.com

need to take a look at those, thanks
i'm not up for rbl, but I'll check other 2

Didn't read all of the posts, but going back to the original subject, you could use pop b4 relay. I had a similar problem where I ended up on aol's list, and we had to close our relay, but in closing our relay we locked out those folks who accessed our pop3 via a dial-up or some other type of dynamic connection on a different net. To fix it I installed a popb4 relay that logs IP addresses after a successful pop3 log in, and then when the smtp server is accessed it scans the database for the particular IP, if it is in there it sends if not it gives a relaying denied message. Go to http://sendmail.org and search for Pop Before Relay or something along those lines and you will find it. The one I use it called poprelayd and it interfaces with sendmail fairly easily (relative to the rest of sendmail), and it works beautifully. If this was already solved ignore what I said, otherwise I hope this helps!