digraph email {
size = "20,20";
nodesep=3.5;
ranksep=0.5;
margin=0;
nodesep=LR;


edge [fontsize=12];

fontname="Times-Italic";


subgraph cluster0 {
node [shape=polygon,sides=4,peripheries=2,style=filled]
PHP1 [label="PHP"];
PHP1 -> nullmailer [label="sendmail", weight=200]
label="hosting";
}


subgraph cluster1 {
node [shape=polygon,sides=4,peripheries=2,style=filled]
PHP2 [label="PHP"]; 
crond;
Postfix;
crond -> Postfix [taillabel="sendmail", weight=200, labeldistance=1.5];
PHP2 -> Postfix [label="sendmail", weight=1];
label="services";
}

{
edge [style=dotted];
email -> PHP1;
email -> crond [weight=15];
email -> PHP2 [weight=10];
}


Internet [shape=Msquare];

nullmailer -> Postfix [label="SMTP", labeldistance=3];

Postfix -> Internet [label="SMTP"];

}