I fully understand now, thank you for the response!

I have a list of about 1,000-2,000 members and I noticed that when I sent it out last it failed after getting only about half-way through. This was on MercuryC(planning on changing to E) and I didn't have either the explode or VERP functions on.

Any advice in addition to turning explode and VERP on. Can I change the number of undeliverables to a higher number before the whole list quits? Will the explode function make it so that there would have to be 20x5 fails instead of just 1x5 fails for the whole list to stop sending out?

Thanks! 

> I have a list of about 1,000-2,000 members and I noticed that when I sent it out last it failed after getting only about half-way through.
> This was on MercuryC(planning on changing to E) and I didn't have either the explode or VERP functions on.

1 message with 1000 to 2000 addresses will cause a lot of servers to choke.  VERP error handling would provide a separate message for each member of the list, a fanout of 20 would send 20 message with 50-100 addresses.   

>
> Any advice in addition to turning explode and VERP on. Can I change the number of undeliverables to a higher number before the whole list
> quits?

The number of undeliverables should have little or no affect here.

> Will the explode function make it so that there would have to be 20x5 fails instead of just 1x5 fails for the whole list to stop sending out?

I thought for sure that when I looked through the logs of the outgoing messages, it reached 5 failures and then the whole stopped being delivered to the rest.

Does this sound familiar? 

 I thought for sure that when I looked through the logs of the outgoing

messages, it reached 5 failures and then the whole stopped being

delivered to the rest.

This is the typical error seen if you are sending via MercuryC and the receiving server has set a limit on the number of bad RCPT TO addresses for a single message.  This can also happen if the server sets a limit on the number of RCPT TO addresses in a single message.  If you were using VERP this would not happen since each message has on one RCPT TO address.