in 1 minute check..

MAIL SOCKET MANAGEMENT
count number of mail connections (miscconn[user].sock!=-1 && miscconn[user].type==2)
 if less than MAX_MAIL_CONNECTIONS
  while ((count_current_mail_connections < MAX_MAIL_CONNECTIONS) && (tries <= 2))
	find free mail slot
		if there is one
			do_mail_connect()
				if bad connect, increase tries, continue through while
				if good, tries = 0
		if not ABORT
 if not less than MAIL_CONNECTIONS or over # of tries
	ABORT

MAIL CONNECTION MANAGEMENT:
if (do_smtp_mail) {
do directory read of maildir/outgoing/ counting (need_connections) up to
MAX_MISC_CONNECTS;


in main while() loop..

if socket readable
	get input
	if (stage==0 && input contains banner)
		stage=1 ready=1
	if (stage==1 && input contains good helo reply)
		stage=2 ready=1
	if (stage==2 && input contains good sender reply)
		stage=3 ready=1
	if (stage==3 && input contains good recipient reply)
		stage=4 ready=1
	if (stage==4 && input contains good DATA reply)
		stage=5 ready=1
	if (stage==5 && input contains good message reply)
		stage=2 ready=1
		remove queue file
		reset file fd,queuename
	continue through readacble sockets

if socket writeable
	if (ready) {
		if (stage==1) {
		write helo
		ready=0
		}
		if (stage==2) {
		readdir outgoing/ for first queue file
		if no queue file exists, close connection, continue;
		else rename/move first queue file to outgoing_active/
		fopen queue file
		fd=FILEHANDLE
		queuename=FILENAME
		read first line
		write out sender
		if write fails
			close file
			move queuename back to outgoing/
			close connection
		ready=0;
		}
		if (stage==3) {
		read next line
		write out recipient
		if write fails
			close file
			move queuename back to outgoing/
			close connection
		ready=0;
		}
		if (stage==4) {
		write out "DATA"
		if write fails
			close file
			move queuename back to outgoing/
			close connection
		ready=0;
		}
		if (stage==5) {
		reading next line from file
		write out body line
		if write fails
			close file
			move queuename back to outgoing/
			close connection
		else loop read/write till end
		ready=0;
		}
	}



MAIL COMPOSITION

FILE *get_mailqueue_file(void) {
time_t tm;
int subtime=0;
static FILE *tfp;

	tm=time(0);

	sprintf(filename,"%s/%s%ld.%d",OUTGOING_MAILDIR,(long)tm,subtime);
	while ((tfp=fopen(filename,"r")) && subtime != 100) {
		fclose(tfp);
		subtime++;
		sprintf(filename,"%ld.%d",(long)tm,subtime);
	}
	if (subtime==100) {
		write_log(ERRORLOG,YESTIME,"Could not open a new queue file in fmail()\n");
		return NULL;
	}
	else {
	 if (!(tfp=fopen(filename,"w"))) {
		write_log(ERRORLOG,YESTIME,"Could not open the new queue file %s in fmail()
		\n",filename);
		return NULL;
	 }
	 else return tfp;
	}

	return NULL;
}

	if (!(wfp=get_mailqueue_file())) {
		error
	}

	fprintf(wfp,"%s\n",SYSTEM_EMAIL);
	fprintf(wfp,"%s\n",mail_addr);
	/* start body */

	fclose(wfp);


SMTP CONVERSATION:

220 stevenjude2.compustrat.com ESMTP Postfix
HELO stevenjude2.compustrat.com
250 stevenjude2.compustrat.com
MAIL FROM: joe@blow.com
250 Ok
RCPT TO: receiver@blow.com
250 Ok
DATA
354 End data with <CR><LF>.<CR><LF>

BAD HELO:
HELO
501 Syntax: HELO hostname

BAD FROM:
MAIL FROM:
500 Error: bad syntax

BAD RCPT:
RCPT TO:
501 Syntax: RCPT TO: <address>


FUNCTIONS:
void check_smtp(void);
int do_smtp_connect(void);
FILE *get_mailqueue_file(void);
int queuetoactive_smtp(int user);
int write_smtp_data(int user, int type);
void requeue_smtp(int user);
void check_misc_connects(void);
int find_queue_slot(char *inpstr);


ERROR/FAILURE/SUCCESS CODES:
         211 System status, or system help reply
         214 Help message
            [Information on how to use the receiver or the meaning of a
            particular non-standard command; this reply is useful only
            to the human user]
         220 <domain> Service ready
         221 <domain> Service closing transmission channel
         250 Requested mail action okay, completed
         251 User not local; will forward to <forward-path>
          
         354 Start mail input; end with <CRLF>.<CRLF>
          
         421 <domain> Service not available,
             closing transmission channel
            [This may be a reply to any command if the service knows it
            must shut down]
         450 Requested mail action not taken: mailbox unavailable
            [E.g., mailbox busy]
         451 Requested action aborted: local error in processing
         452 Requested action not taken: insufficient system storage
          
         500 Syntax error, command unrecognized
            [This may include errors such as command line too long]
         501 Syntax error in parameters or arguments
         502 Command not implemented
         503 Bad sequence of commands
         504 Command parameter not implemented
         550 Requested action not taken: mailbox unavailable
            [E.g., mailbox not found, no access]
         551 User not local; please try <forward-path>
         552 Requested mail action aborted: exceeded storage allocation
         553 Requested action not taken: mailbox name not allowed
            [E.g., mailbox syntax incorrect]
         554 Transaction failed


COMMAND-REPLY SEQUENCES:
"P" = preliminary
"I" = intermediate
"S" = success
"F" = failure
"E" = error

            CONNECTION ESTABLISHMENT
               S: 220
               F: 421
            HELO
               S: 250
               E: 500, 501, 504, 421
            MAIL
               S: 250
               F: 552, 451, 452
               E: 500, 501, 421

            RCPT
               S: 250, 251
               F: 550, 551, 552, 553, 450, 451, 452
               E: 500, 501, 503, 421
            DATA
               I: 354 -> data -> S: 250
                                 F: 552, 554, 451, 452
               F: 451, 554
               E: 500, 501, 503, 421
            RSET
               S: 250
               E: 500, 501, 504, 421
            SEND
               S: 250
               F: 552, 451, 452
               E: 500, 501, 502, 421
            SOML
               S: 250
               F: 552, 451, 452
               E: 500, 501, 502, 421
            SAML
               S: 250
               F: 552, 451, 452
               E: 500, 501, 502, 421
            VRFY
               S: 250, 251
               F: 550, 551, 553
               E: 500, 501, 502, 504, 421
            EXPN
               S: 250
               F: 550
               E: 500, 501, 502, 504, 421
            HELP
               S: 211, 214
               E: 500, 501, 502, 504, 421
            NOOP
               S: 250
               E: 500, 421
            QUIT
               S: 221
               E: 500
            TURN
               S: 250
               F: 502
               E: 500, 503