-(@ref{Postfix, look how} Postfix SMTP server could be configured)
-commands to queue file, freq and exec transmissions. Repeat as
-many times any time as you wish.
+(look @ref{Postfix, how} Postfix and @ref{Exim, how} Exim SMTP servers
+could be configured) commands to queue file, freq and exec
+transmissions. Repeat as many times any time as you wish.