What do the letters F T S R and E mean in Sendmail milter? I see on sendmail.mc milters lines like this: Xclamantivirus, S=local:/var/run/clamav-milter/clamav.sock,F=T,T=S:4m;R:4m;E:4m I know what is a local socket. But what do the letters F T S R and E mean ?

All but "E:" is explained in _Scanning e-mail for virusses with ClamAV and Sendmail_ by Peter Kaagman. Reformatting and fixing a few typos:

> **`S=`**`local:/var/run/clamav/clmilter.sock` of course is the socket created by clamav-milter
>
> **`F=`** tells Sendmail what to do if the filter fail, blank means act as if there is no filter. You could use "R" for reject or "T" for temporary fail.
>
> **`T=`** determines timeouts:
>
> **`S:4m`** a timeout of 4 minutes for sending to the filter
>
> **`R:4m`** a timeout of 4 minutes for receiving from the filter