diff --git a/docs/core/plugins/imap_sieve.md b/docs/core/plugins/imap_sieve.md
index f09c7e9ae..e0fcf86bf 100644
--- a/docs/core/plugins/imap_sieve.md
+++ b/docs/core/plugins/imap_sieve.md
@@ -108,6 +108,14 @@ This plugin registers the `imapsieve` extension with the Sieve
 interpreter. This extension is enabled implicitly, which means that it
 does not need to be added to the [[setting,sieve_extensions]] setting.
 
+## Dovecot-specific Environment Items
+
+The `imapsieve` extension ([[rfc,6785]]) defines environment items for the `environment` extension ([[rfc,5183]]). Beyond those, Dovecot provides additional environment items via the `vnd.dovecot.imapsieve` extension (enabled with `require "vnd.dovecot.imapsieve";`):
+
+- `vnd.dovecot.mailbox-from`: The source mailbox from which the message is being copied or moved (populated during IMAP `COPY` or `MOVE` commands).
+- `vnd.dovecot.mailbox-to`: The destination mailbox to which the message is being copied. When not executing from an IMAP `COPY` or `MOVE` command, this is equal to `imap.mailbox`.
+
+
 ## Example Configuration
 
 ```doveconf[dovecot.conf]
diff --git a/docs/core/plugins/sieve_imapsieve.md b/docs/core/plugins/sieve_imapsieve.md
index 5cb290466..33b9cc3e3 100644
--- a/docs/core/plugins/sieve_imapsieve.md
+++ b/docs/core/plugins/sieve_imapsieve.md
@@ -13,6 +13,8 @@ The `sieve_imapsieve` plugin implements the `imapsieve` extension
 for the Sieve filtering language, adding functionality for using Sieve
 scripts from within IMAP.
 
+It also provides the Dovecot-specific `vnd.dovecot.imapsieve` extension, which exposes environment items such as `vnd.dovecot.mailbox-from` (source mailbox during IMAP `COPY`/`MOVE`) and `vnd.dovecot.mailbox-to` (destination mailbox).
+
 ::: tip
 Full details about this plugin can be found at [[plugin,imap-sieve]].
 :::