I'd have to go with a 99.99% likelihood that the email is being spoofed. This has been going on for years. Over the past couple of weeks I've noticed a substantial increase.

One of the main reasons for spoofing an email address is to get the content (spam) past any spam filters. You can use SPF and several other techniques, but a simple technique is to blacklist specific emails to specific accounts. For example, you could specifically blacklist an address and prevent it from receiving email from itself.

Another good preventive practice is to use email aliasing. These are throwaway addresses that can be deleted anytime they end up on a spammers list.

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