You can easily purchase additional mailboxes for Titan Email by opening the Emails section and selecting your domain:
And clicking Buy Email Accounts:
You will be presented with a pop-up window, where you will be able to purchase additional email accounts with just a few clicks:
All of your email mailboxes have to have the same expiry date. For example, 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
That’s it, now you know how to add additional mailboxes to your email account 😊