That works out to one email every 9 seconds, so I would go with one email every 10 seconds at the highest.
Currently throttling is not possible with SMTP, so you will need to enable the "Internal PHP mail" sending option.
Next, enter the following delays for 1 per 10 seconds:
Delay [10000] ms every email and
- mins every [999] messages
On this host a message to just one thousand subscribers would take two and a half hours. A typical server is capable of over 100,000 messages per day. I recommend finding a host with a more fair email policy. Some shared hosts allowing up to 25,000 messages per day with no hourly limits are mentioned here:
http://listmailpro.com/forum/index.php?topic=1699.0Please let me know if I can be of further assistance!
Regards