That depends from your MTS. Specifically, it depends from what local delivery agent your mail server is using. For exim's appendfile
transport, for example, the administrator might have used the quota_warn_threshold
and quota_warn_message
options to ensure that a warning message is delivered to a user whose mailbox is close to filling to its assigned quota. For Courier's deliverquota
delivery agent, the administrator might have used the -w
option to ensure a similar warning message be given to the user.
Since you don't tell us the LDA or how it is configured, the rest of the world won't be able to give you an answer.