There are settings to limit the number sending.
g_sent_backoff
g_send_speed
g_send_delay
g_send_retry_552
g_send_to_limit (can set for particular domains)

Have you tried these yet?
I used to send a blast of ~5,000 and by slowing down the sending, things 
went smoother.

On 1/26/2012 10:30 PM, Frank Bulk wrote:
> This is an ongoing issue for us.  Could one of the SurgeMail developers comment?
>
> Frank
>
> -----Original Message-----
> From: Frank Bulk [mailtoHIDDEN@mypremieronline.com]
> Sent: Wednesday, January 18, 2012 10:32 PM
> To: surgemailHIDDEN@etwinsite.com
> Subject: [SurgeMail List] Message fan out
>
> We watch our outbound queues pretty closely and nearly every time a particular church sends out an email blast we're blocked by yahoo.com and uiowa.edu for a short time because we hit some kind of threshold.  Within the hour the block is removed and those messages are delivered.
>
> When we were using our Barracudas to process outbound mail it would fan out multi-recipient messages -- I know that SurgeMail can fan out individual messages across multiple outbound IPs, but is there an option in SurgeMail to fan out multi-recipient messages (of the type I described above) so that they're spread across all the outbound IPs?
>
> Frank
>
>
>
>