.PS
# stunnel

L: box wid 2 ht 2
box invis "local host" below with .n at L.n

#P: box wid 0.3 ht 3 with .e at L.w

P465: box wid 0.3 ht 0.3 with .e at 0.25<L.nw,L.sw> "465"
P25: box wid 0.3 ht 0.3 with .e at 0.75<L.nw,L.sw> "25"

left
line <- 1.0 left from P465.w "SMTP over TLS" "(encrypted)"
box dashed "remote" "host"

spline -> from P465.e right 0.4 then to 0.5<P465.s, P25.n> then to P25.w-(0.4,0) then to P25.w "stunnel"

right
line -> 0.5 right from P25.e "SMTP" "(unencrypted)"
box "MTA"


.PE