.. _storage_side_metadata: ============================ Storage-Side Object Metadata ============================ When saving data to object storage, Dovecot stores metadata associated with each blob for data recovery purposes. This data is written to the HTTP endpoint by adding Dovecot metadata headers to the request. When retrieving a message from object storage, this data is returned in the received headers (only parsed by Dovecot if needed). The header name used is specific to the obox driver: ========== =============================== Driver Metadata Header ========== =============================== s3 x-amz-meta-dovecot- sproxyd X-Object-meta-dovecot- ========== =============================== The metacache keys available are: =============== ======================================== =========================================================== ============================== ======================================== Key Description Max Length (in bytes) Data Type Other =============== ======================================== =========================================================== ============================== ======================================== username Dovecot unique username N/A (installation dependent) email guid Message guid 32 email size Message size (in bytes) 20 (in theory; rarely more than 10) email received Received date (unix timestamp) 20 (in theory; rarely more than 10) email saved Saved date (unix timestamp) 20 (in theory; rarely more than 10) email pop3uidl POP UIDL N/A (depends on source installation) email Only if message migrated pop3order POP message order 10 email Only if needed by migration origbox Folder guid of first folder where 32 email stored(copying does not update this) fname Dovecot filename N/A - installation dependent email Dictmap only (username component) username Dovecot unique username N/A (installation dependent) index size Bundle size (in bytes) 20 (in theory; rarely more than 10) index fname Dovecot filename N/A - installation dependent index Dictmap only (username component) mailbox-guid Mailbox guid the index refers to 32 index Dictmap only username Dovecot unique username N/A (installation dependent) fts fname Dovecot filename N/A - installation dependent (username component) fts Dictmap only =============== ======================================== =========================================================== ============================== ========================================