"CiviCRM works well except that CiviMail is limited by outbound mail throttle of 100/hr from Dreamhost anti-spam policy. (200/hr for shell accounts.) DH may be willing to lift the throttle under compliance with strict rules. Shared hosting environment also causes variable response times (less politely, the page load times are crap for some accounts, mainly due to slow MySQL query times)" - via http://bit.ly/3xACTb
That description is accurate as far as our policies go. You'll definitely break your email if you try to use CiviCRM to send a bulk emailing of 5,000 contacts! If you can prove you are anti-spam policy compliant (re: opt-in confrimations) we could only increase your mailing quota to 500 per hour, so at best you would have a 10 hour process to mail to 5,000 contacts.
An announcement list with 5,000 contacts will self-throttle over several hours. Unfortunately, the email service we offer in conjunction with our hosting plans is not designed for mass-email services.
If you do need to send bulk email in high quantities like that, we recommend you use a service designed for that (you can do this easily with custom MX records you can point to a higher-voulme friendly service).
However you send your emails, please be aware of our anti-spam policy to avoid risking account termination. More info can be had here: http://bit.ly/rUJZnz and here: http://bit.ly/VyN9zp
Hope this helps! If you have any questions, please reply here or email us! http://bit.ly/PfpbbY