>>> Do spammers try to guess mx servers which look similar to the one (or two >>> or... :-) published in the DNS?
They don't guess. They intentionally hit your secondary and tertiary, in the expectation that it has a lesser level of spam protection. Confidentiality Notice This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential or proprietary information which is legally privileged. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please promptly contact the sender by reply e-mail and destroy all copies of the original message.
