Fresh from consecutive victories on the 3G surface at Skegness Sports Association, United's hopes of a hat-trick of home wins were soon extinguished by a strong Pools side.
Hartlepool led 3-0 at half-time and added two further goals in the last five minutes.
Boston (4-4-2): Jake Frestle; James Mallender (Joe Hardstaff 52), Harry Cranfield, Brogan Horniman, Nathan Stevens; Jamie Gaukroger, Finlay Armond, Ashton Taylor (Daniel Fisher 46), Jack Bastow (Tom Wilkinson 46); Will Jackson, Xander Crashley. Subs (not used): Josh Burkitt, Craig Forbes.
Referee: Michael Brader.