With more people shopping online, the postman will be working harder to get those packages delivered.
From July 12, they will be delivered on Saturdays as well, said Singapore Post.
Its call centre services also run 24 hours each day now, to cater to online shoppers who may want to enquire about their deliveries day or night.
To help its mailmen with their growing loads, SingPost is giving them bigger, more comfortable three-wheelers that can hold more parcels.
Online shoppers and the popularity of e-commerce have thrown a lifeline to postal service operators as letter volumes wane.
SingPost's domestic mail volumes fell for the second consecutive year last year, with letter volume shrinking the most.
However, mail packages in total jumped 50 per cent between 2007 and last year.
This figure looks set to increase. Market research firm Euromonitor Internationalestimated that Singapore consumers will spend more than $1 billion online this year on purchases such as clothes, consumer electronics and media products - 9 per cent more than the $960 million they spent last year.
Said SingPost chief executive Wolfgang Baier: "We recognise that customers who make online purchases are naturally eager to receive their packages."
Online shopper Miguel Ho, 27, who is a civil servant, said: "This is great. If they deliver on weekdays, I tend to be out and will have to go to the post office to collect my package."
"Even better if they deliver my package on Saturday mornings, when I am at home," he added.
SingPost used to make deliveries on Saturdays but stopped in 2010 after there were 40 per cent fewer letters for delivery on Saturdays than on weekdays.
But it is confident there is demand for a Saturday package delivery service due to more people shopping online.
Its 24/7 call centre also caters to online shoppers who may have queries about postage when they shop at night, SingPost said.
Previously, the company's call centre operated from 8am to 6pm on weekdays, and 8am to 1pm on Saturdays.
The changes will be funded by some $100 million that SingPost has set aside to modernise postal infrastructure and improve customer service standards, it said. The bulk of this - $45 million - will be spent on new, more efficient mail-sorting machines that will sort packages too.
"Increasing productivity is a priority," said Dr Baier. He was speaking at a breaking fast event at the SingPost Centre in Eunos, which Minister-in-charge of Muslim Affairs Yaacob Ibrahim also attended.
SingPost also announced that the SingPost Inclusivity Fund launched last year has helped lower-income earners cope with the rising cost of living. Front-liners, such as postmen, received a 10 per cent wage increase over two years from this fund.
And the 60 new three-wheelers, which will be deployed in the next three months, will make their job more comfortable.
They are more powerful, and have a roof to protect mailmen from rain and shine, four new compartment boxes and an enlarged box to provide 25 per cent more space than the first generation of three-wheelers launched in 2011.
Said postman Kamarol Zamal Atan, 50: "We used to deliver more letters than parcels but increasingly, we are delivering more bulky items due to online shopping. The second-generation three-wheeler will help me pack more parcels and make more deliveries at one go," he said.