How Mail Hosting works

A Mail Hosting service gives people mailboxes on your own domain. They read and send mail in a mail app over IMAP and SMTP, over JMAP, or in webmail. You manage everything from the service's panel in the dashboard: go to Mail Services and open the service. The public Mail Hosting page describes the product, with its prices from the catalogue.

Domains

The names your addresses end in, such as example.com. You add a domain, prove you own it and publish its DNS records. See Add a domain to Mail Hosting.

Mailboxes

Addresses that store mail and can sign in, such as alex@example.com. Each has its own password and storage quota. See Create and manage mailboxes.

Aliases

Extra addresses that deliver to one or more mailboxes on the service, including a catch-all for a whole domain. See Forward addresses with aliases.

A mailbox or alias can only use a domain on the same service, and the dashboard offers only domains that are verified. Each domain can be on one mail service at a time.

The plan sets how many mailboxes and domains the service may hold, and how much storage it has. The storage is one pool for the whole service: the number of mailboxes multiplied by the storage per mailbox that the plan lists.

Each mailbox takes a share of that pool as its quota. A new mailbox gets an equal share by default, and you can give one mailbox more and another less, as long as the quotas together fit in the pool. The smallest quota is 100 MB.

Aliases do not count against the plan. To get more mailboxes, domains or storage, see Move to a bigger or smaller plan.

In the dashboard, go to Mail Services, open the service, then the Overview tab.

The four figures at the top show Storage, Mailboxes and Domains used against the plan, and the number of Aliases. A bar turns amber above 70% of its limit. It turns red only when the service holds more than the plan allows, such as after a move to a smaller plan.

Finish setting up

Comes first while a domain still waits for its DNS records, or while the service has no domain yet. It names each waiting domain, says what is left and what the last check found, and has Show DNS records, which opens the domain's page. With no domain yet, it has Add domain… instead, which opens the Add a domain page. The card goes away once every domain is verified.

Mail client setup

The settings a mail app asks for, in the order it asks. See Connect a mail app.

Mail server addresses

The names to enter in a mail app: SMTP (ports 587 with STARTTLS and 465 with TLS), IMAP (port 993 with TLS) and JMAP (port 8443). It also shows the Webmail address.

Sending

How many emails the mailboxes sent this month, with a bar for each day they sent mail. Choose 7d, 30d or 90d beside the title to change the days the bars cover. Under the bars are Delivered as a share of what was sent, Bounced and Complaints for those days. Mail Hosting has no monthly sending limit.

Recent activity

The latest delivery events from the last seven days, such as delivered, bounced or deferred messages.

Service

The service's Status, Plan, Region, the date it Renews, when it was Created and its Service ID. When we pause the service's sending, the status reads Sending paused.

Plan and add-ons

Once account plans open on your account, what the plan gives the service and the add-ons on it (The Plan and add-ons card).

Tags

Labels you add to find the service. See Tags.

Domains

Each domain and its verification status. Select one to open its DNS records.

The panel header has Open webmail, which opens the webmail address in a new tab, and Order another, which opens the Mail Hosting order page for a second service. Once account plans open on your account, Order another leaves the header: your plan includes the Mail Hosting, and the Extra Mailbox add-on adds mailboxes to it. On that service's Overview tab, Add mailboxes in the Plan and add-ons card opens the add-on's page, and /dashboard/mail/<id>/overview?add=mailboxes takes you to it on arrival. On the Mail Hosting your account plan includes, the header also has an Included in your plan badge. While all of the service's domains still wait for their DNS records, the status beside its name reads Waiting for DNS records in place of Active.

Once account plans open on your account, some terms are underlined with dots. IMAP and SMTP are on the Mail client setup card, JMAP on the Mail server addresses card, and MX and DKIM on the Domains card. A waiting domain's count of passed checks, such as Pending · 2/5, is underlined on the Finish setting up card and on the domain's page. Select one for a short explanation and Read more in the glossary, which opens its glossary entry.

A mailbox sends through the service's SMTP server after it signs in. The rules that apply to every mail service apply to it too:

• The From address must be on a domain of the service that has passed its ownership check.
• A recipient on the service's suppression list is refused with Recipient … is suppressed after a bounce or complaint. Bounces and spam complaints add addresses to it.
• The service has an hourly sending limit, rate_per_hour in the service summary, which is 200 messages an hour for each domain unless our staff set another. Each mailbox may also send up to 200 messages an hour. Mail over a limit waits in the queue and goes out in a later hour. Mail Hosting has no monthly sending limit.
• Mail you send leaves through shared sending. Coritan runs the mail platform: mailboxes, queues, authentication (SPF, DKIM and DMARC), abuse controls and sending limits. Coritan is building out its own shared sending pool, and until it is ready, shared sending uses a delivery partner.
• We watch each service's bounce and complaint rates. When they cross the pause threshold, we pause the service and the panel shows Sending is paused. Until our staff lift the pause, its mailboxes cannot sign in, send or receive mail. See Sending reputation and deliverability.

To send mail from an application rather than a person, use SMTP Relay.

When you cancel the service and it ends, we delete its mailboxes, aliases and stored mail. Move anything you want to keep first.

Read the service summary:

curl https://api.coritan.com/api/v1/client/mail/4812 \
  -H "Authorization: Bearer $CORITAN_TOKEN"

The fields you need most:

kind

hosting for Mail Hosting.

status

active once the service is ready.

quota_mailboxes, quota_domains, quota_storage_bytes

What the plan allows. quota_storage_bytes is the whole pool.

counts

How many of each thing the service holds: mailbox, alias, group and domains.

used_bytes

The storage the mailboxes use.

rate_per_hour

The service's hourly sending limit.

hostnames

smtp_host, imap_host and jmap_host for mail apps, jmap_port, the port JMAP and CardDAV answer on (8443), webmail_url, and mx_hostname_base, which ends the mx1, mx2 names your domains' MX records point to.

cluster.region, cluster.region_name

The region the service runs in: its code, and its name, such as Frankfurt, or null when we have no name for it.

sending_frozen, review_flag, reputation_note

Whether sending is paused or under review, and why.

service

The service's id, status and hostname.

A service that is still being set up answers 409 with This mail service is still provisioning.