The Department of Posts, Telecommunication and Information Technology issued the letter on Thursday, ordering all postal service employees to join offices from next week.
The government announced a general holiday, initially from Mar 26-Apr 4 before extending it to Apr 11, in a bid to reduce the risk of a further outbreak.
But the shutdown order will not apply to emergency services such as electricity, water, gas, fire services, cleaning activities, telephone, newspapers and the internet.
Post and Telecommunication Minister Mustafa Jabbar, the letter said, had ordered continuation of postal services in public interest during the virus shutdown.
Sub-post offices in the metropolitan cities have also been instructed to remain open from Sunday on a limited scale. The postmaster generals will decide which offices will remain open during the shutdown period.
Transportation, operated by the department of posts itself, will be available in the daytime only to provide emergency services to district-level offices.
Deputy and postmaster generals have been asked to contact local administration to provide services to Upazila-level offices.
The minister also asked them to take ‘all safety and precautionary measures’ in cash and treasury transactions.