diff --git a/deltachat-ffi/deltachat.h b/deltachat-ffi/deltachat.h
index 8fc483a72..1f37b1e2f 100644
--- a/deltachat-ffi/deltachat.h
+++ b/deltachat-ffi/deltachat.h
@@ -3485,7 +3485,7 @@ int             dc_contact_is_verified       (dc_contact_t* contact);
  *     accessor functions.  If no provider info is found, NULL will be
  *     returned.
  */
-dc_provider_t*  dc_provider_new_from_domain           (char* domain);
+dc_provider_t*  dc_provider_new_from_domain           (const char* domain);
 
 
 /**
@@ -3499,7 +3499,7 @@ dc_provider_t*  dc_provider_new_from_domain           (char* domain);
  *     accessor functions.  If no provider info is found, NULL will be
  *     returned.
  */
-dc_provider_t*  dc_provider_new_from_email            (char* email);
+dc_provider_t*  dc_provider_new_from_email            (const char* email);
 
 
 /**
diff --git a/deltachat-ffi/src/lib.rs b/deltachat-ffi/src/lib.rs
index a1214bc58..04981bd2b 100644
--- a/deltachat-ffi/src/lib.rs
+++ b/deltachat-ffi/src/lib.rs
@@ -225,8 +225,8 @@ pub unsafe extern "C" fn dc_get_userdata(context: *mut dc_context_t) -> *mut lib
 #[no_mangle]
 pub unsafe extern "C" fn dc_open(
     context: *mut dc_context_t,
-    dbfile: *mut libc::c_char,
-    blobdir: *mut libc::c_char,
+    dbfile: *const libc::c_char,
+    blobdir: *const libc::c_char,
 ) -> libc::c_int {
     if context.is_null() || dbfile.is_null() {
         eprintln!("ignoring careless call to dc_open()");
@@ -298,8 +298,8 @@ pub unsafe extern "C" fn dc_get_blobdir(context: *mut dc_context_t) -> *mut libc
 #[no_mangle]
 pub unsafe extern "C" fn dc_set_config(
     context: *mut dc_context_t,
-    key: *mut libc::c_char,
-    value: *mut libc::c_char,
+    key: *const libc::c_char,
+    value: *const libc::c_char,
 ) -> libc::c_int {
     if context.is_null() || key.is_null() {
         eprintln!("ignoring careless call to dc_set_config()");
@@ -322,7 +322,7 @@ pub unsafe extern "C" fn dc_set_config(
 #[no_mangle]
 pub unsafe extern "C" fn dc_get_config(
     context: *mut dc_context_t,
-    key: *mut libc::c_char,
+    key: *const libc::c_char,
 ) -> *mut libc::c_char {
     if context.is_null() || key.is_null() {
         eprintln!("ignoring careless call to dc_get_config()");
@@ -369,8 +369,8 @@ fn render_info(
 #[no_mangle]
 pub unsafe extern "C" fn dc_get_oauth2_url(
     context: *mut dc_context_t,
-    addr: *mut libc::c_char,
-    redirect: *mut libc::c_char,
+    addr: *const libc::c_char,
+    redirect: *const libc::c_char,
 ) -> *mut libc::c_char {
     if context.is_null() {
         eprintln!("ignoring careless call to dc_get_oauth2_url()");
@@ -612,7 +612,7 @@ pub unsafe extern "C" fn dc_maybe_network(context: *mut dc_context_t) {
 pub unsafe extern "C" fn dc_get_chatlist(
     context: *mut dc_context_t,
     flags: libc::c_int,
-    query_str: *mut libc::c_char,
+    query_str: *const libc::c_char,
     query_id: u32,
 ) -> *mut dc_chatlist_t {
     if context.is_null() {
@@ -733,7 +733,7 @@ pub unsafe extern "C" fn dc_send_msg(
 pub unsafe extern "C" fn dc_send_text_msg(
     context: *mut dc_context_t,
     chat_id: u32,
-    text_to_send: *mut libc::c_char,
+    text_to_send: *const libc::c_char,
 ) -> u32 {
     if context.is_null() || text_to_send.is_null() {
         eprintln!("ignoring careless call to dc_send_text_msg()");
@@ -1017,7 +1017,7 @@ pub unsafe extern "C" fn dc_get_chat_contacts(
 pub unsafe extern "C" fn dc_search_msgs(
     context: *mut dc_context_t,
     chat_id: u32,
-    query: *mut libc::c_char,
+    query: *const libc::c_char,
 ) -> *mut dc_array::dc_array_t {
     if context.is_null() || query.is_null() {
         eprintln!("ignoring careless call to dc_search_msgs()");
@@ -1054,7 +1054,7 @@ pub unsafe extern "C" fn dc_get_chat(context: *mut dc_context_t, chat_id: u32) -
 pub unsafe extern "C" fn dc_create_group_chat(
     context: *mut dc_context_t,
     verified: libc::c_int,
-    name: *mut libc::c_char,
+    name: *const libc::c_char,
 ) -> u32 {
     if context.is_null() || name.is_null() {
         eprintln!("ignoring careless call to dc_create_group_chat()");
@@ -1131,7 +1131,7 @@ pub unsafe extern "C" fn dc_remove_contact_from_chat(
 pub unsafe extern "C" fn dc_set_chat_name(
     context: *mut dc_context_t,
     chat_id: u32,
-    name: *mut libc::c_char,
+    name: *const libc::c_char,
 ) -> libc::c_int {
     if context.is_null() || chat_id <= constants::DC_CHAT_ID_LAST_SPECIAL as u32 || name.is_null() {
         eprintln!("ignoring careless call to dc_set_chat_name()");
@@ -1151,7 +1151,7 @@ pub unsafe extern "C" fn dc_set_chat_name(
 pub unsafe extern "C" fn dc_set_chat_profile_image(
     context: *mut dc_context_t,
     chat_id: u32,
-    image: *mut libc::c_char,
+    image: *const libc::c_char,
 ) -> libc::c_int {
     if context.is_null() || chat_id <= constants::DC_CHAT_ID_LAST_SPECIAL as u32 {
         eprintln!("ignoring careless call to dc_set_chat_profile_image()");
@@ -1322,7 +1322,7 @@ pub unsafe extern "C" fn dc_get_msg(context: *mut dc_context_t, msg_id: u32) ->
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn dc_may_be_valid_addr(addr: *mut libc::c_char) -> libc::c_int {
+pub unsafe extern "C" fn dc_may_be_valid_addr(addr: *const libc::c_char) -> libc::c_int {
     if addr.is_null() {
         eprintln!("ignoring careless call to dc_may_be_valid_addr()");
         return 0;
@@ -1334,7 +1334,7 @@ pub unsafe extern "C" fn dc_may_be_valid_addr(addr: *mut libc::c_char) -> libc::
 #[no_mangle]
 pub unsafe extern "C" fn dc_lookup_contact_id_by_addr(
     context: *mut dc_context_t,
-    addr: *mut libc::c_char,
+    addr: *const libc::c_char,
 ) -> u32 {
     if context.is_null() || addr.is_null() {
         eprintln!("ignoring careless call to dc_lookup_contact_id_by_addr()");
@@ -1349,8 +1349,8 @@ pub unsafe extern "C" fn dc_lookup_contact_id_by_addr(
 #[no_mangle]
 pub unsafe extern "C" fn dc_create_contact(
     context: *mut dc_context_t,
-    name: *mut libc::c_char,
-    addr: *mut libc::c_char,
+    name: *const libc::c_char,
+    addr: *const libc::c_char,
 ) -> u32 {
     if context.is_null() || addr.is_null() {
         eprintln!("ignoring careless call to dc_create_contact()");
@@ -1369,7 +1369,7 @@ pub unsafe extern "C" fn dc_create_contact(
 #[no_mangle]
 pub unsafe extern "C" fn dc_add_address_book(
     context: *mut dc_context_t,
-    addr_book: *mut libc::c_char,
+    addr_book: *const libc::c_char,
 ) -> libc::c_int {
     if context.is_null() || addr_book.is_null() {
         eprintln!("ignoring careless call to dc_add_address_book()");
@@ -1390,7 +1390,7 @@ pub unsafe extern "C" fn dc_add_address_book(
 pub unsafe extern "C" fn dc_get_contacts(
     context: *mut dc_context_t,
     flags: u32,
-    query: *mut libc::c_char,
+    query: *const libc::c_char,
 ) -> *mut dc_array::dc_array_t {
     if context.is_null() {
         eprintln!("ignoring careless call to dc_get_contacts()");
@@ -1521,8 +1521,8 @@ pub unsafe extern "C" fn dc_get_contact(
 pub unsafe extern "C" fn dc_imex(
     context: *mut dc_context_t,
     what: libc::c_int,
-    param1: *mut libc::c_char,
-    _param2: *mut libc::c_char,
+    param1: *const libc::c_char,
+    _param2: *const libc::c_char,
 ) {
     if context.is_null() {
         eprintln!("ignoring careless call to dc_imex()");
@@ -1545,7 +1545,7 @@ pub unsafe extern "C" fn dc_imex(
 #[no_mangle]
 pub unsafe extern "C" fn dc_imex_has_backup(
     context: *mut dc_context_t,
-    dir: *mut libc::c_char,
+    dir: *const libc::c_char,
 ) -> *mut libc::c_char {
     if context.is_null() || dir.is_null() {
         eprintln!("ignoring careless call to dc_imex_has_backup()");
@@ -1585,7 +1585,7 @@ pub unsafe extern "C" fn dc_initiate_key_transfer(context: *mut dc_context_t) ->
 pub unsafe extern "C" fn dc_continue_key_transfer(
     context: *mut dc_context_t,
     msg_id: u32,
-    setup_code: *mut libc::c_char,
+    setup_code: *const libc::c_char,
 ) -> libc::c_int {
     if context.is_null()
         || msg_id <= constants::DC_MSG_ID_LAST_SPECIAL as u32
@@ -1623,7 +1623,7 @@ pub unsafe extern "C" fn dc_stop_ongoing_process(context: *mut dc_context_t) {
 #[no_mangle]
 pub unsafe extern "C" fn dc_check_qr(
     context: *mut dc_context_t,
-    qr: *mut libc::c_char,
+    qr: *const libc::c_char,
 ) -> *mut dc_lot_t {
     if context.is_null() || qr.is_null() {
         eprintln!("ignoring careless call to dc_check_qr()");
@@ -1660,7 +1660,7 @@ pub unsafe extern "C" fn dc_get_securejoin_qr(
 #[no_mangle]
 pub unsafe extern "C" fn dc_join_securejoin(
     context: *mut dc_context_t,
-    qr: *mut libc::c_char,
+    qr: *const libc::c_char,
 ) -> u32 {
     if context.is_null() || qr.is_null() {
         eprintln!("ignoring careless call to dc_join_securejoin()");
@@ -2577,7 +2577,7 @@ pub unsafe extern "C" fn dc_msg_get_setupcodebegin(msg: *mut dc_msg_t) -> *mut l
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn dc_msg_set_text(msg: *mut dc_msg_t, text: *mut libc::c_char) {
+pub unsafe extern "C" fn dc_msg_set_text(msg: *mut dc_msg_t, text: *const libc::c_char) {
     if msg.is_null() {
         eprintln!("ignoring careless call to dc_msg_set_text()");
         return;
@@ -2590,8 +2590,8 @@ pub unsafe extern "C" fn dc_msg_set_text(msg: *mut dc_msg_t, text: *mut libc::c_
 #[no_mangle]
 pub unsafe extern "C" fn dc_msg_set_file(
     msg: *mut dc_msg_t,
-    file: *mut libc::c_char,
-    filemime: *mut libc::c_char,
+    file: *const libc::c_char,
+    filemime: *const libc::c_char,
 ) {
     if msg.is_null() || file.is_null() {
         eprintln!("ignoring careless call to dc_msg_set_file()");
diff --git a/src/e2ee.rs b/src/e2ee.rs
index 80c7ea5fd..18d0f318d 100644
--- a/src/e2ee.rs
+++ b/src/e2ee.rs
@@ -345,20 +345,17 @@ pub fn try_decrypt(
                     }
                 }
 
-                match decrypt_if_autocrypt_message(
+                encrypted = decrypt_if_autocrypt_message(
                     context,
                     in_out_message,
                     &private_keyring,
                     &public_keyring_for_validate,
                     &mut signatures,
                     &mut gossip_headers,
-                ) {
-                    Ok(res) => {
-                        encrypted = res;
-                    }
-                    Err(err) => {
-                        bail!("failed to decrypt: {}", err);
-                    }
+                )?;
+                if !gossip_headers.is_null() {
+                    gossipped_addr =
+                        update_gossip_peerstates(context, message_time, imffields, gossip_headers)?;
                 }
                 if !gossip_headers.is_null() {
                     gossipped_addr =
@@ -463,7 +460,7 @@ fn update_gossip_peerstates(
     message_time: i64,
     imffields: *mut mailimf_fields,
     gossip_headers: *const mailimf_fields,
-) -> HashSet<String> {
+) -> Result<HashSet<String>> {
     // XXX split the parsing from the modification part
     let mut recipients: Option<HashSet<String>> = None;
     let mut gossipped_addr: HashSet<String> = Default::default();
@@ -498,15 +495,15 @@ fn update_gossip_peerstates(
                             Peerstate::from_addr(context, &context.sql, &header.addr);
                         if let Some(ref mut peerstate) = peerstate {
                             peerstate.apply_gossip(header, message_time);
-                            peerstate.save_to_db(&context.sql, false).unwrap();
+                            peerstate.save_to_db(&context.sql, false)?;
                         } else {
                             let p = Peerstate::from_gossip(context, header, message_time);
-                            p.save_to_db(&context.sql, true).unwrap();
+                            p.save_to_db(&context.sql, true)?;
                             peerstate = Some(p);
                         }
                         if let Some(peerstate) = peerstate {
                             if peerstate.degrade_event.is_some() {
-                                handle_degrade_event(context, &peerstate);
+                                handle_degrade_event(context, &peerstate)?;
                             }
                         }
 
@@ -523,7 +520,7 @@ fn update_gossip_peerstates(
         }
     }
 
-    gossipped_addr
+    Ok(gossipped_addr)
 }
 
 fn decrypt_if_autocrypt_message(
diff --git a/src/securejoin.rs b/src/securejoin.rs
index 373f9bca3..208aaaf29 100644
--- a/src/securejoin.rs
+++ b/src/securejoin.rs
@@ -717,21 +717,24 @@ fn encrypted_and_signed(mimeparser: &MimeParser, expected_fingerprint: impl AsRe
     }
 }
 
-pub fn handle_degrade_event(context: &Context, peerstate: &Peerstate) {
+pub fn handle_degrade_event(context: &Context, peerstate: &Peerstate) -> Result<(), Error> {
     // - we do not issue an warning for DC_DE_ENCRYPTION_PAUSED as this is quite normal
     // - currently, we do not issue an extra warning for DC_DE_VERIFICATION_LOST - this always comes
     //   together with DC_DE_FINGERPRINT_CHANGED which is logged, the idea is not to bother
     //   with things they cannot fix, so the user is just kicked from the verified group
     //   (and he will know this and can fix this)
     if Some(DegradeEvent::FingerprintChanged) == peerstate.degrade_event {
-        let contact_id: i32 = context
-            .sql
-            .query_get_value(
-                context,
-                "SELECT id FROM contacts WHERE addr=?;",
-                params![&peerstate.addr],
-            )
-            .unwrap_or_default();
+        let contact_id: i32 = match context.sql.query_get_value(
+            context,
+            "SELECT id FROM contacts WHERE addr=?;",
+            params![&peerstate.addr],
+        ) {
+            None => bail!(
+                "contact with peerstate.addr {:?} not found",
+                &peerstate.addr
+            ),
+            Some(contact_id) => contact_id,
+        };
         if contact_id > 0 {
             let (contact_chat_id, _) =
                 chat::create_or_lookup_by_contact_id(context, contact_id as u32, Blocked::Deaddrop)
@@ -747,4 +750,5 @@ pub fn handle_degrade_event(context: &Context, peerstate: &Peerstate) {
             emit_event!(context, Event::ChatModified(contact_chat_id));
         }
     }
+    Ok(())
 }
diff --git a/src/wrapmime.rs b/src/wrapmime.rs
index ac3b704cb..fa1f900e0 100644
--- a/src/wrapmime.rs
+++ b/src/wrapmime.rs
@@ -36,7 +36,6 @@ pub fn get_ct_subtype(mime: *mut Mailmime) -> Option<String> {
         let ct: *mut mailmime_content = (*mime).mm_content_type;
 
         if !ct.is_null() && !(*ct).ct_subtype.is_null() {
-            println!("ct_subtype: {}", to_string((*ct).ct_subtype));
             Some(to_string((*ct).ct_subtype))
         } else {
             None
@@ -48,10 +47,12 @@ pub fn get_autocrypt_mime(
     mime_undetermined: *mut Mailmime,
 ) -> Result<(*mut Mailmime, *mut Mailmime), Error> {
     /* return Result with two mime pointers:
-       First mime pointer is to the multipart-mime message
-       (which is replaced with a decrypted version later)
-       Second one is to the encrypted payload.
-       For non-autocrypt message an Error is returned.
+
+    First mime pointer is to the multipart-mime message
+    (which is replaced with a decrypted version later)
+
+    Second one is to the encrypted payload.
+    For non-autocrypt message an Error is returned.
     */
     unsafe {
         ensure!(