I am a newbie. My apologies, if I am stating something very dumb.

I run a web portal with about 20,000 subscribers. I need to send them a newsletter twice a month. I have done the following:

I have added SPF record/DomainKeys for my domain. I do need to use SMTP authentication so that I can handle bounces properly. Mail::Bulkmail would have been a good choice, but I could not figure out if it supports SMTP authentication

What I see here works for me. I just have couple of question

• Can I use Bulkmail instead, if it supports SMTP authentication
• Would it work, if I group addresses by domain and stuff into the To field and then do as many sends as there are domains. There could be thousands addresses for each domain
• If not, instead of doing a new in the loop, can I do the new outside the loop and replace the 'To' field within the loop. Any performance gain there?