Mail Configuration

Mail Configuration gives you control over mailbox storage limits, sending rates, greylisting, and queue delivery behavior directly from the dashboard. No SSH or config file editing required.

Mailbox quotas

Quotas limit how much storage each mailbox can use. When a user reaches their quota, Dovecot rejects new messages with a "mailbox full" error until they free up space.

Global default quota

1. Go to Settings > Mail > Mailbox Quotas
2. Toggle quotas on
3. Set the default quota (e.g., 1 GB)
4. Click Save

The default quota applies to every mailbox that does not have a per-user override.

Per-user quota overrides

You can set a custom quota for individual users that overrides the global default:

1. Go to the Users page
2. Click the edit (pencil) icon on any user
3. Uncheck "Use server default" and enter a custom quota
4. Click Save

The Quota column in the users table shows "Default" for users using the global quota and the specific quota (e.g., "500 MB") for users with a custom override.

To remove a per-user override and revert to the server default, edit the user and check "Use server default" again.

How it works

CeyMail enables the Dovecot quota plugin and configures it to enforce limits via the count backend. Quota values are stored per-user in the database. A value of 0 means "use the global default."

Rate limits

Rate limiting prevents any single client from sending excessive email, protecting your server's IP reputation and preventing abuse.

Configuration

1. Go to Settings > Mail > Rate Limits
2. Toggle rate limiting on
3. Configure the limits:
   • Messages - maximum messages per time period (required)
   • Connections - maximum SMTP connections per time period (0 = unlimited)
   • Recipients - maximum recipients per time period (0 = unlimited)
4. Choose the time period: per hour or per day
5. Click Save

What gets limited

All three limits apply per client IP address and share the same time period. When a client exceeds any limit, Postfix temporarily rejects additional requests with a 450 error. The client's mail server will automatically retry later.

Greylisting

Greylisting temporarily rejects email from unknown senders, requiring them to retry after a delay. Legitimate mail servers always retry; most spam bots do not.

Configuration

1. Go to Settings > Mail > Greylisting
2. Toggle greylisting on
3. Set the delay (1-60 minutes). The default is 5 minutes.
4. Click Save

How it works

CeyMail uses Postgrey as the greylisting policy server. When enabled:

1. CeyMail installs and configures Postgrey automatically
2. Postfix is configured to check Postgrey before accepting mail
3. First-time sender/recipient/IP combinations are temporarily rejected
4. After the configured delay, retries from the same combination are accepted
5. Known sender/recipient pairs are whitelisted for 35 days

When you disable greylisting, CeyMail stops the Postgrey service and removes it from the Postfix policy chain.

Queue & delivery

These settings control how Postfix handles undeliverable messages - how long it retries before giving up, and how frequently it retries.

Configuration

Go to Settings > Mail > Queue & Delivery and adjust:

• Queue lifetime - how long Postfix retries delivery before sending a bounce notification to the sender (default: 5 days)
• Bounce lifetime - how long bounce notification messages themselves are retried (default: 5 days)
• Min retry interval - the shortest time between delivery attempts for a deferred message (default: 300 seconds)
• Max retry interval - the longest time between delivery attempts, reached after repeated failures (default: 4,000 seconds)

How retry intervals work

Postfix uses exponential backoff between delivery attempts. The first retry happens after the minimum interval. Each subsequent retry waits longer, up to the maximum interval. Lower values deliver faster but generate more server traffic. Higher values are gentler on destination servers but delay delivery.

When to adjust these

• Reduce queue lifetime if you want senders notified faster when delivery fails (e.g., 1 day instead of 5)
• Increase queue lifetime if destination servers have extended downtime windows
• Reduce retry intervals for time-sensitive mail that needs faster delivery attempts
• Increase retry intervals to reduce load on your server and be gentler on destination servers

Settings summary