The Peterlee, County Durham-based company made the £500,000 purchase off the back of a strong period of growth for the firm in 2007.
The new kit, which can deliver up to 14,000 items an hour from a single line, joins five existing Buhrs machines at the mailing firm.
MetroMail managing director Alan Purvis said the new Buhrs machines are key to the firm's strategy "to become the most efficient and lean mailing house in the UK".
He said that the mailing house has worked with Buhrs lines for over nine years and "they’ve outlasted equivalent lines from all the other manufacturers we have on site".
Purvis added that operators at MetroMail's £6m, 8,360sqm facility "fight over" the Buhrs kit "because they just run and run".
MetroMail also runs kit including eight Xerox DocuPrint digital presses, three Heidelberg Stahl Folders, a Polar guillotine and two Winkler & Dunnebier envelope manufacturing machines.
MetroMail takes on Buhrs kit as part of 1.7m spend
MetroMail has invested in three BB700 envelope inserting systems from Buhrs as part of a 1.7m spend by the mailing house.