Hi, we are a new and small charity which until now had a mailing list which was tiny (c400). Through a joint campaign with another much larger charity, we now have a mailing list of over 20,000. I feel sure I can't just write and send a newsletter without doing more preparation. For example, I think it would take far too long to send (several days) at the rate I am used to. Please advise. What do I need to do to get the newsletter out safely and with minimum spam problems?