add: basic smtpd configuration options

smtprelay.ini

@@ -30,6 +30,33 @@
 ; accepting mails from client.
 ;local_forcetls = false
 
+; Socket timeout for read operations
+; Duration string as sequence of decimal numbers,
+; each with optional fraction and a unit suffix.
+; Valid time units are "ns", "us", "ms", "s", "m", "h".
+;read_timeout = 60s
+
+; Socket timeout for write operations
+; Duration string as sequence of decimal numbers,
+; each with optional fraction and a unit suffix.
+; Valid time units are "ns", "us", "ms", "s", "m", "h".
+;write_timeout = 60s
+
+; Socket timeout for DATA command
+; Duration string as sequence of decimal numbers,
+; each with optional fraction and a unit suffix.
+; Valid time units are "ns", "us", "ms", "s", "m", "h".
+;data_timeout = 5m
+
+; Max concurrent connections, use -1 to disable
+;max_connections = 100
+
+; Max message size in bytes
+;max_message_size = 10240000
+
+; Max RCPT TO calls for each envelope
+;max_recipients = 100
+
 ; Networks that are allowed to send mails to us
 ; Defaults to localhost. If set to "", then any address is allowed.
 ;allowed_nets = 127.0.0.0/8 ::1/128
@@ -83,4 +110,4 @@
 ;remote_sender = 
 
 ; Pipe messages to external command
-;command = /usr/local/bin/script
+;command = /usr/local/bin/script