Improve follow checking when a DM arrives

follow.py

@@ -126,6 +126,7 @@ def _removeFromFollowRejects(baseDir: str,
 def isFollowingActor(baseDir: str,
                      nickname: str, domain: str, actor: str) -> bool:
     """Is the given nickname following the given actor?
+    The actor can also be a handle: nickname@domain
     """
     if ':' in domain:
         domain = domain.split(':')[0]
@@ -137,6 +138,12 @@ def isFollowingActor(baseDir: str,
         return False
     if actor.lower() in open(followingFile).read().lower():
         return True
+    if '@' in actor and '://' not in actor:
+        # the actor is a handle: nickname@domain
+        followingHandle = actor.lower()
+        if followingHandle in open(followingFile).read().lower():
+            return True
+        return False
     followingNickname = getNicknameFromActor(actor)
     if not followingNickname:
         print('WARN: unable to find nickname in ' + actor)

inbox.py

@@ -40,6 +40,7 @@ from categories import setHashtagCategory
 from httpsig import verifyPostHeaders
 from session import createSession
 from session import getJson
+from follow import isFollowingActor
 from follow import receiveFollowRequest
 from follow import getFollowersOfActor
 from follow import unfollowerOfAccount
@@ -73,7 +74,6 @@ from git import receiveGitPatch
 from followingCalendar import receivingCalendarEvents
 from happening import saveEventPost
 from delete import removeOldHashtags
-from follow import isFollowingActor
 from categories import guessHashtagCategory
 from context import hasValidContext
 
@@ -2288,8 +2288,9 @@ def _inboxAfterInitial(recentPostsCache: {}, maxRecentPosts: int,
                             sendH = \
                                 sendingActorNickname + '@' + sendingActorDomain
                             if sendH != nickname + '@' + domain:
-                                if sendH not in \
-                                   open(followingFilename).read():
+                                if not isFollowingActor(baseDir,
+                                                        nickname, domain,
+                                                        sendH):
                                     print(nickname + '@' + domain +
                                           ' cannot receive DM from ' +
                                           sendH +