The sixty-second answer
Most small businesses need one paid mailbox for each person who sends email, and nothing more. Role addresses such as info@, sales@ and accounts@ should be aliases pointing at those mailboxes, or shared mailboxes when a team works the queue. Count senders, not addresses. Addresses are free to invent; mailboxes are what you pay for.
The question behind the question
Almost nobody actually wants to know how many email addresses they need. What they want to know is how big the bill is going to be, and whether they are about to be charged for something they could have had for nothing. That is a fair worry, because the two things get deliberately blurred in a lot of quotes.
So start with the distinction that decides the answer. A mailbox is storage with a login attached: somewhere messages sit, and a set of credentials that opens it. An address is a label that routes mail to a mailbox. An alias is an address with no storage of its own. The mail standards are unambiguous about this. When a server expands an alias, it replaces the address in the envelope with the real destination and leaves the rest of the envelope and the message body untouched, then delivers it [1]. Nothing is stored twice. Nothing extra is provisioned. An alias is, at the level of the protocol, a redirect.
That is why the honest answer to "how many addresses do I need" is: as many as you like. The number that costs money is how many mailboxes you need, and that number is usually smaller than people expect.
How to count properly
Write down every person in your business who needs to send email from your domain. That is your mailbox count. Then write down every address you want customers to be able to write to. That is your alias list, and it is free-form.
A two-person contracting business might come out of this exercise with two mailboxes - joel@ and the other partner - and six addresses: two personal ones, plus info@, quotes@, accounts@ and jobs@, all aliased onto the two real mailboxes. To the customer this looks like a company with departments. On the invoice it is two seats.
This is not a fringe scenario. As of December 2024 there were 1.10 million employer businesses in Canada, and 1.08 million of them - 98.2 per cent - were small businesses [4]. The typical Canadian buyer of business email has a handful of staff and a strong incentive to look larger than they are. Aliases are the cheapest way to do that honestly, because the mail really does reach a person who really does answer.
When does a role address need its own mailbox?
Three situations genuinely justify paying for a seat that is not a person:
Someone has to reply as the address. If a customer emails accounts@ and needs a reply that also comes from accounts@ - because it goes into their accounts payable system, or because your bookkeeper should not be exposing a personal address - you need a real mailbox with real credentials behind it.
More than one person works the queue. The moment two people are answering support@, an alias becomes a liability. Both get a copy, neither knows whether the other has replied, and the customer gets answered twice or not at all. What you want here is a shared mailbox: one store, several people with access. IMAP has this built in. The protocol defines an Other Users' Namespace where a user must be explicitly granted access rights to see someone else's folders, and a Shared Namespace for mailboxes that are meant to be shared and do not belong to any one person [2]. The access-control extension lets those rights be set per user and per mailbox, with different rights required for different operations [3].
The mailbox has to outlive the person. Anything tied to a contract, a regulator, a bank or a domain registrar should live in a mailbox the business owns, not in a staff member's personal one. This is the single most common reason a small business loses access to something important - it was registered to a departed employee's address. We wrote about that failure mode in what to do with an employee's email account when they leave.
Outside those three cases, an alias is the right tool. The full comparison of addresses, aliases and shared mailboxes is in business email addresses, aliases and shared mailboxes.
The pattern to avoid: one login, several humans
The tempting shortcut is to buy one mailbox and give the password to everyone. It works, briefly, and then it fails in ways that are hard to unwind.
You lose attribution: nobody can say who sent the message that caused the problem. You lose offboarding: when someone leaves, the only remedy is to change a password that four other people are also using. And you lose the ability to answer a straightforward privacy question. Under PIPEDA's Schedule 1, an individual is entitled on request to be informed of the existence, use and disclosure of their personal information and to be given access to it [5]; the same schedule requires knowledge and consent for collection and use, and forbids using information for new purposes without consent. If five people share one login and one of them forwarded a customer's file somewhere, you cannot answer any of those questions. A shared mailbox with per-user access rights gives you the same convenience and keeps the audit trail. Our overview of business email privacy obligations in Canada goes through this in more depth.
The other pattern to avoid: forwarding everything to a free account
The mirror-image shortcut is to create addresses on your domain and forward them all to a personal free-provider account. This looks like it costs nothing. In practice you have created a redistribution path that mail authentication has to be taught about, and you have put your business correspondence in an account you do not administer and cannot audit. If you are weighing that option, read why a business email address on your own domain beats a free address and whether to use a shared inbox or just forward the mail before you build on it.
What over-buying actually costs
Buying too many mailboxes is not just a monthly overcharge. Each unused seat is a live account with a password, a login surface, and mail arriving into it that nobody reads. Dormant mailboxes are where password reuse goes to be discovered, and where a customer's urgent message sits unanswered for three weeks because the address is on a business card nobody has thrown away.
The cheaper failure is the reverse - a real person sharing someone else's seat - and that is the one to guard against as you grow. The rule of thumb that survives both: a mailbox is a person or a queue, never a topic.
How to read a per-mailbox price
When you compare providers, the headline number per mailbox is the least informative part of the quote. Ask instead:
Are aliases included, and is there a cap? Do shared mailboxes consume a seat? How much storage comes with a seat, and what happens when it fills? Is there a mandatory setup or migration charge? Can you add and remove seats mid-term, or are you buying a year? What is the price to move the mail out again?
That last set of questions is not paranoia, it is what a price actually means. Canadian law is on your side here: the Competition Act's drip-pricing provision treats an advertised price that cannot be attained because fixed obligatory charges have been excluded as a false or misleading representation in its own right, carving out only charges imposed under an Act of Parliament or a provincial legislature [6]. Tax on top is legitimate. A compulsory onboarding fee that surfaces at checkout is not.
Where we sit
MapleMail is billed per mailbox, on your own domain, hosted in Canada. Aliases are the part we do not meter, because at the protocol level they are a routing rule rather than a resource. Shared mailboxes exist for the queues that genuinely need more than one person in them, with access granted per user rather than by handing out a password.
We do not publish plan prices in articles, because they change and an article does not; the current figures live on the pricing page, alongside what each seat includes. What we will commit to in writing is the shape: you pay for people, you do not pay for labels, and adding an address should never require adding a seat.
If you are sizing this out for the first time, do the two-column exercise above before you talk to anyone. Senders on the left, addresses on the right. The left column is your quote. The right column should be free.