Despite the fact that Japan has the world's largest market for digital-manga, which are primarily read on cellphones, and that Amazon has recently brought out its Kindle platform in Japan — after a delay of 5 years — the e-book business here has yet to take off. As such, it's probably no surprise that old-style digital content in the form of merumaga (paid e-mail newsletters) is blooming in the Japanese Web scene, though the scale of the business is still small.
Similar to many Net-related terms, the word merumaga is English, er ... kind of. Taking the first part of English words to form new terms is quite common in Japan —for example Pokemon comes from "Pocket Monster." Merumaga is an abbreviated word made from "mail magazine," which is not exactly a common English expression, but you can guess that it means e-mail newsletter. The more exact Japanese word nyūsuretā is not as instinctive and doesn't make for a nice abbreviation for Japanese.
Starting in the late 1990's, periodical newsletters began sprouting from certain corners of the Japanese Internet. There are several merumaga newsstands, which are websites that distribute scheduled e-mails to anywhere from just a few, to thousands of different recipients. This includes cellphone e-mail addresses, to which you can not usually send bulk messages from PC-based software. Each cellphone carrier has different limitations, rules and anti-spam filters which often flag e-mails from PCs as spam, so when people in Japan began merumaga they tended to use these newsstand services to ensure their newsletters got through to their subscribers.