A mail domain is the part of an email address after the @ sign. It has to exist before any mailboxes can be created in it, and it is where the settings common to all those mailboxes are held — spam protection, what happens to mail sent to non-existent addresses, and encryption.
Creating a mail domain
- Go to the Mail section.
- Click Mail domains on the toolbar.
- Click Create a mail domain.
- Enter the Name — the domain itself, for example example.com.
- Select the IP address that mail will be sent from.
- Choose the Default action (see below).
- Save the changes.
You can then create mailboxes in this domain — see Creating a mailbox in ISPmanager.
Mail to non-existent addresses
The Default action decides what happens when someone writes to an address that does not exist in your domain:
- Report error — the sender is told the address does not exist. This is the sensible default: a genuine correspondent learns they have the wrong address.
- Ignore and delete — the sender gets an error and the message is discarded.
- Forward to address — everything goes to one address you specify. Convenient, but it collects a great deal of spam, since addresses that do not exist are exactly what spammers guess at.
- Forward to domain — the mail server looks for the mailbox in another mail domain instead. Note that this does not work if you specify a mailbox alias as the target.
Spam and virus protection
These are enabled for the whole domain, and can then be turned on or off for individual mailboxes:
- Greylisting — temporarily defers mail from unknown senders. Legitimate servers retry and get through; many spam senders do not. Worth knowing that it can delay the first message from a new correspondent by a few minutes.
- SpamAssassin — scores incoming mail and marks likely spam.
- Virus scanning — checks attachments with ClamAV.
DKIM and DMARC
Both are worth enabling. Without them, mail from your domain is far more likely to be treated as spam by large mail providers, and your domain is easier to forge.
- Enable DKIM — signs your outgoing mail so that receiving servers can verify it really came from your domain. The required TXT record is created automatically. Choose a key length of 2048.
- Enable DMARC — tells receiving servers what to do with mail that fails these checks. The TXT record is again created automatically.
These records only take effect if your domain's DNS is served from this server. If DNS is hosted elsewhere, the records have to be copied to that provider by hand — open a ticket if you need help with that.
Encrypting mail traffic
Enable Secure connection (SSL) and choose a Let's Encrypt certificate. It is free, trusted by mail clients and renewed automatically.
A self-signed certificate is also offered, but mail clients will warn about it every time, so it is only suitable for internal testing.
Managing existing mail domains
In the Mail domains list you can edit a domain's settings, replace its certificate, or disable it — a disabled domain makes all its mailboxes unavailable without deleting anything.
Deleting a mail domain deletes the mail. All mailboxes in it are cleared, and without a backup the messages cannot be recovered. Disable the domain instead if you are not certain.
Before mail will work
Creating the mail domain in the panel is only half of it: the domain's MX records must point to this server, otherwise mail continues to be delivered wherever they currently point. If you are moving mail from another provider, set up the mailboxes first and change the MX records afterwards, so that nothing arrives before there is somewhere to put it.
If mail is not being delivered after the change, open a ticket from your client area with the domain name.
