Installing outbound SMTP server on CentOS

[Kevin Miller]

I'm setting up an outbound server so I have a single egress point from our internal network.  I'll be running MailScanner on it primarily so that I can set the watermarking feature to help control joe-job blowback.  I have three existing inbound gateways that aren't currently using watermarking.  I thought I'd post here for a quick reality check before shooting myself in the foot.

My plan is is to assign all four hosts (one outbound, and three inbound) the same watermark per the comments in MailScanner.conf, but leave the line 
 "Treat Invalid Watermarks With No Sender as Spam	nothing" 
set to nothing initially so that I can do a bit of testing and watching before going live.

The current settings are:
 Use Watermarking	no
 Add Watermark	yes
 Check Watermarks With No Sender	yes
 Treat Invalid Watermarks With No Sender as Spam	nothing
 Check Watermarks To Skip Spam Checks	yes
 Watermark Secret	<some secret string>
 Watermark Lifetime	604800
 Watermark Header	X-CBJ-MailScanner-Watermark:

When I send a message via one of the gateways I'm not seeing the X-CBJ-MailScanner-Watermark:.  Do I need to set "Use Watermrking" to yes first?  I would think, given the settings, that the watermark header would be added but ignored.  If I go ahead and turn on watermarking but leave the invalid watermark line set to "nothing" will that turn everything on but not actually affect the outcome of the process?  (Sort of like the "~all" parameter in SPF.)

Thanks...

...Kevin
--
Kevin Miller                Registered Linux User No: 307357
CBJ MIS Dept.               Network Systems Admin., Mail Admin.
155 South Seward Street     ph: (907) 586-0242
Juneau, Alaska 99801        fax: (907 586-4500