When international flights ground to a halt earlier this year, it was not only travellers who could not catch a plane.
Outgoing mail from Singapore, which is typically carried in the belly of passenger aircraft, also piled up, resulting in a months-long backlog.
SingPost turned to cargo planes and sea shipments to help move these along, but delays remain as flights are now at about five or six a day, down from 140 pre-pandemic, Singapore's postmaster-general Vincent Phang said in an interview.
As the Republic is a major transshipment hub, this affects not only mail generated here but also items that pass through on the way to other countries, he noted.
Lockdowns in other countries and higher freight charges add to the challenges that the postal service provider is grappling with amid the Covid-19 pandemic.
SingPost last month reported a 12 per cent increase in revenue for the first quarter of the year off a rise in e-commerce deliveries, but profits were dragged down by a 22 per cent increase in expenses.
Asked whether international postal rates are likely to go up as a result of the decrease in air connectivity, Mr Phang said the rates are set by Universal Postal Union, a United Nations agency.
But this issue and boosting air links will likely be topics of discussion when its members meet.
Global supply-chain disruptions, pandemic-related restrictions and a manpower crunch have affected local-mail delivery too, he noted.
During the circuit breaker, for example, SingPost had to extend its storage space to house business mail which could not be redirected.
Malaysia's movement control order, which imposed strict border restrictions, also led to a shortage of manpower as some postmen, who commute to work in Singapore daily, could not return. Those willing to stay here in the meantime have been put up by SingPost.
Several Covid-19 cases among employees in March and April led to quarantines, and the company was down by a few dozen frontline staff at one point, which led to some delays, Mr Phang said.
While there have been some complaints, the public has generally been understanding given the circumstances, he noted.
Customer satisfaction has improved over last year, when it was in the spotlight for a slew of delivery mishaps.
The postal service provider was also fined $400,000 for failing to meet government delivery standards in 2017 and 2018.
Changes put in place late last year to address service issues - including hiring more postmen and directing all packages to the letterbox - have helped it to survive the current operational challenges, he said. "Had we not done that, I think we would be in a world of pain."
The e-commerce boom over the recent months has brought challenges as well as new partnerships.
It began to offer delivery of medicine during the circuit breaker in April, and now delivers high-security items such as passports and identity cards.
There are also plans to work with online sellers to boost smaller basket purchases. "I like to think that Covid-19 presents opportunities," said Mr Phang.
Tiffany Fumiko Tay