newsletter sending / cron / structure

[Feudalism]

Right now im planning to create a newsletter sender module. I have all the smtp servers quite running and ready. My lists are ready too. I need now to programa a Cronjob (I know how to do this too) so every 3 minutes some php file is executed and the mails delivered.

How should my php be?

# get the message to send
# get the list of non-sent email address
# send the message to them in a throttling basis ( 20 each 3 minutes, maybe less, maybe more)
# mark those addresses as "already sent"

As you can see, Im actually more worried about the logic and structure of the file than the coding. I know how to do this in PHP, but... i have a bad feeling about the logic. I was hoping you to help me find some better way to do this, if there is any.

Thanks!

[wheeler]

I think the logic sounds pretty sound...

store the emails in the database with sent ('0','1')
SELECT stuff WHERE sent = '0' LIMIT $whatever
sent
UPDATE row

I do the same thing myself in a email marketing application and it works like a charm.

[atlantadental]

Yes, that logic does sounds right. I do just about the same thing in my own newsletter script.

[crmalibu]

Might want to anticipate the script not finishing on time before the cron job runs again. For example, maybe have 3 states (unsent,sending,sent). You could add a timestamp as well, if you want to be able to handle a script which tried to send, but failed/crashed etc...that way you can detect a "sending" status that is stale.

[Feudalism]

Great responses! I really thank you weeler, atlantadental and crmalibu! . I was worried about the timing of the script, so the CronJob doesn't have problems oversending the e-mails, an I think that is the same source of problem that a correct throttling has.
Im currently coding the module. When I finish it i shall test the throttling.. but anyway... have any of you read about the correct mails per minutes in a Gmail SMTP? I tryed "gmal smtp throttling" on google, but got no accurate results.