I'm writting a shell script to email customers invoices.
after each RCPT to: email@address.com, i've put in a sleep 1 command,
but with 2000 customers to email and about 5 or 6 of these sleep commands it can take a very long time.

Is there any smaller amount of time the sleeper can sleep for that 1 second?

Is that you are going to mail the same subject and content to all the n-receipients?

then a single mailx command would do !!!

First of all why do you need a sleep command when you are sending mails to n-receipients!!!

He may be looking at his queue getting backed up and wants the sleep to avoid it - not that it matters much. The system should just queue them up and send them out.

You can do a sleep 0. That will 'slow' it down for the time that it takes the system to run the sleep command (milliseconds) and then continue on.

Yep thats brilliant. Why didn't I just think out of the box!!
Thanks

Also it could be that each of his 2000 customers gets a different invoice.

A couple solution are mentioned in this thread.