meaning

[Hanka]

Hi,

could you please help me? Does the following sentence make sense to you?

The supplier will send the invoice for the supplied goods, in accordance with article 3 paragraph 2 of this Contract, on the day it is issued to the customer by registered mail, by the 15th day of the following month at the latest.

What does "on the day it is issued" refer to? Does it refer to the date of issue of the invoice? If so, it means that the invoice should be sent on the date of its issuance and not by the 15th day of the following month
Or could it refer to the amount of goods not invoiced until the day of issuance of the invoice?

Thanks a lot!

Hanka

[Anglika]

The supplier will send to the customer by registered mail the invoice for the supplied goods, on the day it is issued [and] by the 15th day of the following month at the latest, in accordance with article 3 paragraph 2 of this Contract.

This is how I would rephrase this clause.