I'm not sure that it would help get past the spam blockers, but any mail you send to multiple large numbers of people should be sent as "BCC" (blind carbon copies). When you send this way, the "blind copy" recipients see only the address you put in the "send to" box and they do not get all the other recipients' email addresses.

It's possible that this would also make it look like an individually addressed message to the spam blockers, but I can't verify that. Whether it helps with the spam blockers, it's really discourteous to publish the email addy's of all the people on your mailing list.

You should have at least one "To" address on the message. You can send the "real" mail to yourself, or to one or two selected people on your list. The BCC addressees' email addy's should not appear on any copy except the one that remains in your "Sent" file, so you need to keep that copy as your "historical" record, if you need one, rather than the one that you actually send to an open address.

John