Q. Can you fix yourself things (paint and other repairs) in the house (on Purim) if it is for the need of Shabbos? Can you text and send emails on Purim?

A. Shulchan Aruch and Remo (O.H. 696:1) permit work on Purim when done for a mitzva. Mishna Berura (ibid. 6) permits also writing congratulatory letters. However, warns one not to over engage in non-Purim related activities, so he will not come to neglect the simcha and joy of Purim.
Horav Shlomo Miller’s Shlit”a opinion is similar.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a.