Period-eccentricity diagram for known post-mass transfer binaries. Recently discovered bloated stripped star binaries with O/Be companions (Shenar et al. 2020; El-Badry & Quataert 2021; Villaseñor et al. 2023; Ramachandran et al. 2024; Pauli et al. 2022) are indicated with red diamond markers. These include the parameter values for HIP 15429 determined in this work. Be + subdwarf binaries with known orbital parameters are shown with light blue triangles (Mourard et al. 2015; Chojnowski et al. 2018; Peters et al. 2008, 2013; Klement et al. 2022, 2024; Wang et al. 2023). We plot the short-period subdwarf binaries compiled by Edelmann et al. (2005) and Kupfer et al. (2015) and long-period (> 500 d orbits) subdwarf binaries discovered by Deca et al. (2012), Barlow et al. (2013), Vos et al. (2012, 2013, 2017) with dark blue triangles. Likely post-common envelope binaries with white dwarf or main-sequence stars analysed by Yamaguchi et al. (2024) are shown with yellow stars.