"We discussed the achieved results with the shareholder. There have been successful projects, financial gains and operational efficiency improvements. This could be, then, the best moment to reach for new horizons," Salnājs told Latvian Radio after his resignation.
The rest of the board - Ilze Bagatska, Arnis Gulbis un Egons Strazdiņš - have also handed in their resignations, reported LTV.
Salnājs declined to comment the Transport Ministry review over management problems at the company as he "hadn't read the report".
On Friday the Transport Ministry told LSM's Latvian-language service that a temporary new board has been put in place, consisting of Mārcis Vilcāns, department head at the Express Post, regional economist Kristaps Krūmiņš, and Ilze Aleksandroviča, deputy State Secretary at the Transport Ministry.
The next board chairman and the board will be picked in an open competition, according to the Transport Ministry.
The ministry explained the resignations with shortcomings in the management of the company. The ministry put blame on the Postal Service for not abiding to State Audit office suggestions on the company's payment system and the number of service cars used by the service, plus there had been unsound decisions over service car rentals.
Earlier this week Transport Minister Uldis Augulis (Greens) told BNS about "several violations and absurdities" related to business trips and premiums paid to employees in the state-owned postal service that operates more than 600 offices across Latvia.
In 2014 Latvijas Pasts increased its turnover 7%, posting €1.7m in profits. There's no data yet about the company's performance last year.
The Transport Ministry will be holding a shareholders' meeting and decide whether to accept the resignations.