Can you resume sending mails to a list of which only part of the addresses are having had a newsletter? I set cron throttle to 500 and then cron to run every hour. Using a shared server on hostgator, apparently this appears to be too much. So what ended up happening is only 1000ish of my 2500 mail address were being sent a simplenews newsletter.

So is there any way of picking up where I left off so these 1000 people will not receive the same mail again (and unsubscribe).  And if not, would there be any way to export the simplenews log in a way where you can easily edit the adresses that were begint a newsletter and make a temporary list?

Update; my question comes down to whether a log of the actual successful (or failed) email adressess is accessible. I've looked into the watchdog table and queried SELECT messages FROM watchdog. This gave me a list where the column that's supposed to contain the 'To:' addresses, actually contains a wildcard. So instead of the value being an actual email adres, the value is %To. 

Yet, on the site, I could go to admin/reports/dblog and would be able to filter simplenews. This way I can consult emailadresses that have been sent, but I would have to click each rown over 1.000 times and then copy/paste the email adres in excel or plain text to create a new list for the remaining addresses? I hope there is a way that I can link these wildcards with their actual address and then be able to export it into something that I can use to bulk operate?
To avoid automated spam testing, most hosting companies avoid reporting back on failed sending. If you somehow know who got and email and who didn't, you could suspend or remove subscription for those who did, send email again and after that re-enable users. That's pretty universal method, works for any mass sending mechanism.

If you don't know who got your email and who didn't, only raw number, you have a problem that's unsolvable.

For the future, Drupal integrates pretty well with some paid mail sending services. That's a solution for sending large amount of mail and keeping page on shared hosting. If you want to avoid mail sending services, virtual private server shouldn't have a limit on sent mail count. Sending mails is pretty expensive in terms of cpu and memory, and it's an outdated technology, so it's only to be expected shared hostings will limit and discourage it, except for small quantities like registration confirmation etc.