Spend on email marketing will hit $2.1 billion by 2012, near double what it is now, reports DestinationCRM.

The prediction was gleaned from a report by JupiterResearch. Over the next four years, budgets for email marketing will rise from $1.2 billion spent in '07 to $2.1 billion spent in '08.

Increased spending follows the rise in online spend, which is only expected to continue.

Jupiter admonishes email marketers ensure their messages are not mislaid as email marketing increases. They must be effectively targeted, the company advises, with clear calls to action.

Some marketing emails may also fall victim to efforts by ISPs to block spam. Delivery rates for "legitimate" emails (such as opt-in messages) are still expected to be around 90 percent.