emailing using ‘Newsletter” -f issue

Hi.
I have spent the best part of a week trying out various email database / email newsletter options.
The nearest thing to perfection is Newsletter.
But I have two issues with it that I hope someone can help me (and others?) with.
The first one is that when a subscriber subscribes, an email is generated by my webhost company thus:
Nobody <[email protected]>
The webhost asked if there was an ‘-f’ option in the plugin – and there is. I made it active but it makes no difference. My webhost is not happy to be generating these ‘nobody’ emails and of course I get one sent every time someone subscribes. Any ideas?
Secondly, my webhost says they would be REALLY grateful if I could time my email distribution list (1400 subs) so each email is let go with a 10-20 gap between each one (so their servers are not overwhelmed during my monthly mail out).
Anyone have a fix to force the emails to be drip fed into the system.

Or, tell me what is working for you. I need double op-in, easy unsubscribe and to send timed newsletters out.

Thanks for your time.