If I pay tuition fees of about 1.5k at Singpost using credit card, will i earn any miles?

Just curious, why singpost? Is that the only payment method?

If there are other methods of payment, it may be better.

Anyways, for singpost, a small 'hack' if you really want to get some extra miles and rewards.

Use CC to topup to Grab wallet (check exclusion list. Most are excluded but still got a few can earn miles)

Use grabpay mastercard to topup NETS Flashpay (NFP) @ GTM (MRT Stations). Everyday cap at $100, each NFP card limit $500.

Use NFP to pay at singpost.

Depends on the credit card you use. Some miles card like OCBC VOYAGE and Citi Premiermiles do not award miles for transactions on tuition payments, so you have to check your card's term and conditions on whether they exclude the merchant code.

Some cards that reward you with miles are HSBC Revolution, BOC Elite Miles World Mastercard, UOB PRVI Miles Card. Similarly, do check out their terms and conditions first as they may only give miles for online spend or other conditions.