PHP mail vs. SMTP

[chief]

What is the difference between the two methods of sending mail in the Subject.

PHP mail
I am having problems keeping the outgoing mail active. It stops with no error or apparent reason. I click RESUME and it starts again, but I have to keep checking. I have it set to do 250 ms per email and 1 min every 250 emails.

I have tried SMTP but it is worse.

I have large lists (>10k) and don't mind slowing the output but need a minimum of 25 email per minute throughput.

I can't afford companies like Rackspace ($383/mo to start) to get high end performance. As I said i don't mind slow-slow outbound mail sending.

Thanks

[DW]

SMTP should be far faster than PHP mail() with delays...  Have you tried writing the SMTP log to see if there is anything wrong?  What MTA (mail server software) does your server use?  Some optimizations are mentioned here in the forum for qmail and Exim that can help things significantly.

Don't even consider $350+ for a dedicated server... A server which can send upwards of 100k messages per day can be had for as low as $75/mo (with a control panel!) from www.domaingurus.com.  The least-powerful processor and 1GB RAM is all you need for email.

There are also shared hosts available for between 10k and 25k per day for $25/mo.  See this post

Regards