#### 3.12.4 Mailbox Quotas ¶

Mailbox quota is a limit on the size of the mailbox. When a mailbox size reaches this limit, `mda` stops accepting messages for this recipient and returns an error condition to the sender. The error code is accompanied by the following error message:

    user: mailbox quota exceeded for this recipient

Furthermore, if accepting the incoming message would make the mailbox size exceed the quota, such a message will be rejected as well. In this case, the error message is:

    user: message would exceed maximum mailbox size for this recipient

In both cases, the default return code will be ‘`service unavailable`’ (corresponding to the SMTP return code ‘`550`’), unless the following statement is present in the `maidag` configuration file:

    quota {
      exit-tempfail yes;
    }

in which case a temporary error will be returned.

The mailbox quota can be retrieved from the following sources:

1. Authentication method.
2. DBM file.
3. SQL database.