SpamAssassin talks about using mailservices to do all filtering. But a research group could be in a situation where it wants two versions installed on their machine; perhaps they don't like IST's cluster, or perhaps they have genuine research need to process locally, or the group just can't agree.

With xhier it's theoretically possible to have two versions installed, even if only one runs spamd.

I tested this with smyth.cs. First I installed spamassin 2.55 on it:

• cscf.cs# xh-dist2 smyth.cs spamassassin-2.55
• smyth.cs# xh-install spamassassin-2.55
• smyth.cs# xh-make-links

This leaves us with spamassin 2.55 as default running. We can call it directly with /software/spamassassin-2.55/bin/spamassassin.

Then I distributed 2.63 to smyth:

• cscf.cs# xh-dist2 smyth.cs spamassassin-2.63
• smyth.cs# xh-install spamassassin-2.63
• smyth.cs# xh-make-links

2.55 is still the default version - I think. Witness:

> cd /software/
> ls -ld spam*
lrwxrwxrwx   1 root     other          17 Jan 25 18:04 spamassassin -> spamassassin-2.55
drwxr-xr-x   8 root     other         512 Jan 25 18:02 spamassassin-2.55
drwxr-xr-x   9 root     other         512 Jan 25 18:19 spamassassin-2.63
>

Let's see what happens after a reboot. Yup, looks ok - 2.55's spamd starts up and 2.63 stays dead. xh-local-maintenance just to be triple sure.