Revert "Drop support for delegating email validation (#13192)" (#13406)

Reverts commit fa71bb18b527d1a3e2629b48640ea67fff2f8c59, and tweaks documentation.

Signed-off-by: 3nprob <git@3n.anonaddy.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/synapse/handlers/ui_auth/checkers.py b/synapse/handlers/ui_auth/checkers.py
index a744d68c64..05cebb5d4d 100644
--- a/synapse/handlers/ui_auth/checkers.py
+++ b/synapse/handlers/ui_auth/checkers.py
@@ -19,6 +19,7 @@ from twisted.web.client import PartialDownloadError
 
 from synapse.api.constants import LoginType
 from synapse.api.errors import Codes, LoginError, SynapseError
+from synapse.config.emailconfig import ThreepidBehaviour
 from synapse.util import json_decoder
 
 if TYPE_CHECKING:
@@ -152,7 +153,7 @@ class _BaseThreepidAuthChecker:
 
         logger.info("Getting validated threepid. threepidcreds: %r", (threepid_creds,))
 
-        # msisdns are currently always verified via the IS
+        # msisdns are currently always ThreepidBehaviour.REMOTE
         if medium == "msisdn":
             if not self.hs.config.registration.account_threepid_delegate_msisdn:
                 raise SynapseError(
@@ -163,7 +164,18 @@ class _BaseThreepidAuthChecker:
                 threepid_creds,
             )
         elif medium == "email":
-            if self.hs.config.email.can_verify_email:
+            if (
+                self.hs.config.email.threepid_behaviour_email
+                == ThreepidBehaviour.REMOTE
+            ):
+                assert self.hs.config.registration.account_threepid_delegate_email
+                threepid = await identity_handler.threepid_from_creds(
+                    self.hs.config.registration.account_threepid_delegate_email,
+                    threepid_creds,
+                )
+            elif (
+                self.hs.config.email.threepid_behaviour_email == ThreepidBehaviour.LOCAL
+            ):
                 threepid = None
                 row = await self.store.get_threepid_validation_session(
                     medium,
@@ -215,7 +227,10 @@ class EmailIdentityAuthChecker(UserInteractiveAuthChecker, _BaseThreepidAuthChec
         _BaseThreepidAuthChecker.__init__(self, hs)
 
     def is_enabled(self) -> bool:
-        return self.hs.config.email.can_verify_email
+        return self.hs.config.email.threepid_behaviour_email in (
+            ThreepidBehaviour.REMOTE,
+            ThreepidBehaviour.LOCAL,
+        )
 
     async def check_auth(self, authdict: dict, clientip: str) -> Any:
         return await self._check_threepid("email", authdict)