Then, click on Get additional email accounts:
You will be presented with a pop-up window where you will be able to choose how many accounts you want to add and purchase them with just a few clicks:
The cost of each additional mailbox is determined by the expiration date of your email plan since all of your email accounts need to have the same expiration date.
For example, if you purchased 1 email account on 2020-03-01 for 6 months for $30 and on 2020-06-01 (after 3 months) you decided that you need to have 2 email accounts overall, in this case, you will pay $15, and the plan will still expire on 2020-09-01.
The calculation works like this:
(Amount of months purchased × Monthly price) / (Full plan time / Time left until plan expiration) × Extra email accounts you are purchasing = (6 × 5) / (6 / 3) × 1
Now you know how to add extra email accounts to your email plan 😊