I have a client who has a list of several thousand emails. He wants to send them a one time email, offering his services. AFAIK it's not spam, because he will only send it once. But there's around a thousand or two for each domain, so if we just send them all at once (via a simple custom PHP script) perhaps the recipient server will take offense and stop them. So we thought to send 20 every hour from 9 am to 6 pm via cron. Then they will not look suspicious. Sounds reasonable? Even though this whole idea sounds like spam, I personally am willing to do this job because I don't think it really will be considered spam--the addresses are somewhat targeted and the letter is very friendly, basically offering his services if they're interested, and if not, they can ignore it. Thanks.