diff --git a/backend/imap/src/main/java/com/fsck/k9/backend/imap/ImapSync.kt b/backend/imap/src/main/java/com/fsck/k9/backend/imap/ImapSync.kt
index cfe5c6b3c..3fe9a0c8f 100644
--- a/backend/imap/src/main/java/com/fsck/k9/backend/imap/ImapSync.kt
+++ b/backend/imap/src/main/java/com/fsck/k9/backend/imap/ImapSync.kt
@@ -75,6 +75,9 @@ internal class ImapSync(
 
             if (syncConfig.expungePolicy === ExpungePolicy.ON_POLL) {
                 Timber.d("SYNC: Expunging folder %s:%s", accountName, folder)
+                if (!remoteFolder.isOpen || remoteFolder.mode != OpenMode.READ_WRITE) {
+                    remoteFolder.open(OpenMode.READ_WRITE)
+                }
                 remoteFolder.expunge()
             }
 
diff --git a/backend/imap/src/test/java/com/fsck/k9/backend/imap/TestImapFolder.kt b/backend/imap/src/test/java/com/fsck/k9/backend/imap/TestImapFolder.kt
index 9e3b6a9d4..306fb43f3 100644
--- a/backend/imap/src/test/java/com/fsck/k9/backend/imap/TestImapFolder.kt
+++ b/backend/imap/src/test/java/com/fsck/k9/backend/imap/TestImapFolder.kt
@@ -17,6 +17,9 @@ open class TestImapFolder(override val serverId: String) : ImapFolder {
     override var mode: OpenMode? = null
         protected set
 
+    override val isOpen: Boolean
+        get() = mode != null
+
     override var messageCount: Int = 0
 
     var wasExpunged: Boolean = false
diff --git a/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/ImapFolder.kt b/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/ImapFolder.kt
index 784cab2b6..1e2195a80 100644
--- a/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/ImapFolder.kt
+++ b/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/ImapFolder.kt
@@ -14,6 +14,7 @@ interface ImapFolder {
     val serverId: String
     val mode: OpenMode?
     val messageCount: Int
+    val isOpen: Boolean
 
     @Throws(MessagingException::class)
     fun exists(): Boolean
diff --git a/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/RealImapFolder.kt b/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/RealImapFolder.kt
index 0bce310d7..0ba66a73b 100644
--- a/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/RealImapFolder.kt
+++ b/mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/RealImapFolder.kt
@@ -46,7 +46,7 @@ internal class RealImapFolder(
     override var mode: OpenMode? = null
         private set
 
-    val isOpen: Boolean
+    override val isOpen: Boolean
         get() = connection != null
 
     override fun getUidValidity(): Long? {
@@ -1073,7 +1073,6 @@ internal class RealImapFolder(
 
     @Throws(MessagingException::class)
     override fun expunge() {
-        open(OpenMode.READ_WRITE)
         checkOpen()
 
         try {
diff --git a/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/RealImapFolderTest.kt b/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/RealImapFolderTest.kt
index 8a849c01f..3a07d118a 100644
--- a/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/RealImapFolderTest.kt
+++ b/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/RealImapFolderTest.kt
@@ -1076,10 +1076,23 @@ class RealImapFolderTest {
         assertThat(uid).isEqualTo("23")
     }
 
+    @Test
+    fun `expunge() on closed folder should throw`() {
+        val folder = createFolder("Folder")
+
+        assertFailure {
+            folder.expunge()
+        }.isInstanceOf<MessagingException>()
+            .hasMessage("Folder Folder is not open.")
+
+        verifyNoMoreInteractions(imapConnection)
+    }
+
     @Test
     fun expunge_shouldIssueExpungeCommand() {
         val folder = createFolder("Folder")
         prepareImapFolderForOpen(OpenMode.READ_WRITE)
+        folder.open(OpenMode.READ_WRITE)
 
         folder.expunge()
 
diff --git a/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/TestImapFolder.kt b/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/TestImapFolder.kt
index 8bd973fe0..12e96f6ad 100644
--- a/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/TestImapFolder.kt
+++ b/mail/protocols/imap/src/test/java/com/fsck/k9/mail/store/imap/TestImapFolder.kt
@@ -18,7 +18,7 @@ internal open class TestImapFolder(
     override var messageCount: Int = 0
         protected set
 
-    var isOpen: Boolean = false
+    override var isOpen: Boolean = false
         protected set
 
     private var openAction: () -> Unit = {}