How quickSMTP stores local messages
Local messages are stored in folder mboxes which is created in the selected work directory. For each domain that you register with quickSMTP a sub-folder will be created with the name of the domain. Each mailbox will have its folder inside the domain folder.
The structure looks like this:
Each message that a user receives is stored in a separate file with unique name inside her/his account directory. Messages are in MSG format which means that if needed, they can be examined with third-party email clients, such as Microsoft Outlook.
For each account you can define retention period in number of days. This period defines how long quickSMTP will store the messages for the specified account. Each message that is past the number of retention days will be erased automatically.
Retention is checked and enforced during housekeeping runs, which are related to queue processing and run right after it.
Please be careful with this functionality, because there is no way to recover messages erased because of exceeded retention period!
Retention policy has two options:
Retention based on arrival time
In this case retention days will be counted from the day on which the message has arrived, regardless if the user has opened it or not.
Retention based on retrieval time
In this case retention days will be counted from the day on which the user has retrieved the message. As retrieval is considered full download of message (issuing RETR command as per POP3 protocol specifications).
You can specify quotas on the number of messages or the number of storage space that each account can use. If one of the two quotas is reached, quickSMTP will inform the user by sending her/him a message and will not accept any new messages until the user frees space by erasing messages.
Messages to users will be sent during housekeeping runs, which happen right after queue processing.
Quotas are specified in megabytes e.g. the minimum that you can specify as quota is 1 MB.