Commercial email delivered without prior consent from the email recipient. Also known as SPAM.

Large amounts of promotional email delivered without permission.

An advertising technique of sending an identical message to a large number of recipients.  Unlike Spam e-mailers, bulk e-mailers tend to have reason to believe the recipients are interested in their products, and bulk-emailers honor requests by recipients to be removed from mailing lists.

mass marketing emails sent unsolicited to recipients.

Commercial email delivered without prior consent from the email recipient. Also called spam email, there is now legislation that can enact criminal penalties against spammers.

The phrase Bulk Email is often looked upon as having the same meaning as the word "spam". Typically, the phrase bulk email is used by low cost email marketing service providers, the phrase "Opt In Email" or "Permission Based" are used by larger email marketing vendors who primary target mid-size to fortune 500 clients with larger marketing budgets. In the late 90's a new phrase "opt-in bulk email" started showing up the on websites selling email marketing services.