Storage-Side Object MetadataΒΆ
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
azure
x-ms-meta-<key>
s3
x-amz-meta-dovecot-<key>
sproxyd
X-Object-meta-dovecot-<key>
Note
Azure enforces metadata names to adhere C# identifier naming conventions. If a name does not comply it fails with: 400 The metadata specified is invalid. It has characters that are not permitted.
The metacache keys available are:
Key
Description
Max Length (in bytes)
Data Type
Other
username
Dovecot unique username
N/A (installation dependent)
guid
Message guid
32
size
Message size (in bytes)
20 (in theory; rarely more than 10)
received
Received date (unix timestamp)
20 (in theory; rarely more than 10)
saved
Saved date (unix timestamp)
20 (in theory; rarely more than 10)
pop3uidl
POP UIDL
N/A (depends on source installation)
Only if message migrated
pop3order
POP message order
10
Only if needed by migration
origbox
Folder guid of first folder where
stored(copying does not update this)
32
fname
Dovecot filename
N/A - installation dependent (username component)
Dictmap only
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 (username component)
index
Dictmap only
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