1 qmail-smtpd     Receive message by SMTP from another host:

     2                    

     3      |             MAIL FROM:<bill@irs.gov>

     4      |             RCPT TO:<joe@heaven.af.mil>

     5      |          

     6      |          Is $RELAYCLIENT set? No.

     7      |          Is heaven.af.mil in rcpthosts? Yes.

     8      |          Accept RCPT.  

     9      V             

    10                    

    11 qmail-queue     Store message safely on disk.

    12                 Trigger qmail-send.

    13      |             

    14      V             

    15                    

    16 qmail-send      Look at envelope recipient, joe@heaven.af.mil.

    17      |          Is heaven.af.mil in locals? Yes.

    18      |          Deliver locally to joe@heaven.af.mil.

    19      V          

    20                    

    21 qmail-lspawn ./Mailbox

    22                    

    23      |          Look at mailbox name, joe.

    24      |          Is joe listed in qmail-users? No.

    25      |          Is there a joe account? Yes.

    26      |          Is joe's uid nonzero? Yes.

    27      |          Is ~joe visible to the qmailp user? Yes.

    28      |          Is ~joe owned by joe? Yes.

    29      |          Give control of the message to joe.

    30      |          Run qmail-local.

    31      V          

    32                    

    33 qmail-local joe ~joe joe '' '' heaven.af.mil bill@irs.gov ./Mailbox

    34                    

    35                 Does ~joe/.qmail exist? No.

    36                 Write message to ./Mailbox in mbox format.