I have always used the mail function, and I suppose it's common-sense that a lot of emails is going to be slower. I find the mail function to be more than adequate in normal circumstances. Adding headers as well is fairly straightforward. The only thing that isn't straightforward is adding attachments, takes a little knowledge about emails to get that working, but Zend Mailer sorts all that out for you if you happen to be using Zend Framework.

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The man who comes back through the Door in the Wall will never be quite the same as the man who went out.

Would like to point out that the mailing class i mentioned earlier does have the option to use the mail() function or straight to a server.

Check it out ;)

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Of course the whole point of a doomsday machine, would have been lost if you keep it a secret.