So the website doesn't mention payment by mail as an option. 

https://www.koodomobile.com/help/how-pay-your-bill

However on the detailed pdf ebill it does state it as an Option

Let me flag a rep for you. 

But in all honesty it would be way easier to pay it via the bank, or via credit card

I know it’s easier and I am trying to push the owners. But like I said, operates very old school...

@bartonvillage 

Koodo accepts cheques and money orders as a form of payment however, due to the length of time it takes to receive and process mailed payments, we strongly recommend using alternative payment options.  Would be much easier to pay online via your Self-serve account or online banking.  This will help prevent late payment fees. 

If choosing to mail payments, you can send payment in the form of a money order or cheque. 

Conditions

• You must send payment stub with your payment and ensure the account number is written on the front of the cheque or money order. (one cheque/money order per account number)

• You should allow 7/10 days for mail delivery and 24 to 48 hours of  processing time. 

• Post-dated cheques are not accepted.

Koodo Mobile
CP 11005
SUCC Centre Ville
Montreal, QC
H3C 4T5

Canada post is so unreliable. Even if they are old school, maybe you can pay via cheque at the bank? This will prevent any late payments if Canada post takes longer than expected to deliver