diff --git a/deltachat-ffi/src/lib.rs b/deltachat-ffi/src/lib.rs
index 54bad19d9..95fca7da2 100644
--- a/deltachat-ffi/src/lib.rs
+++ b/deltachat-ffi/src/lib.rs
@@ -1172,7 +1172,7 @@ pub unsafe extern "C" fn dc_get_msg_info(
     }
     let ffi_context = &*context;
     ffi_context
-        .with_inner(|ctx| message::get_msg_info(ctx, msg_id))
+        .with_inner(|ctx| message::get_msg_info(ctx, msg_id).strdup())
         .unwrap_or_else(|_| ptr::null_mut())
 }
 
@@ -1187,7 +1187,11 @@ pub unsafe extern "C" fn dc_get_mime_headers(
     }
     let ffi_context = &*context;
     ffi_context
-        .with_inner(|ctx| message::get_mime_headers(ctx, msg_id))
+        .with_inner(|ctx| {
+            message::get_mime_headers(ctx, msg_id)
+                .map(|s| s.strdup())
+                .unwrap_or_else(|| ptr::null_mut())
+        })
         .unwrap_or_else(|_| ptr::null_mut())
 }
 
@@ -1202,8 +1206,11 @@ pub unsafe extern "C" fn dc_delete_msgs(
         return;
     }
     let ffi_context = &*context;
+
+    let ids = std::slice::from_raw_parts(msg_ids, msg_cnt as usize);
+
     ffi_context
-        .with_inner(|ctx| message::delete_msgs(ctx, msg_ids, msg_cnt))
+        .with_inner(|ctx| message::delete_msgs(ctx, ids))
         .unwrap_or(())
 }
 
@@ -1250,9 +1257,11 @@ pub unsafe extern "C" fn dc_markseen_msgs(
         eprintln!("ignoring careless call to dc_markseen_msgs()");
         return;
     }
+    let ids = std::slice::from_raw_parts(msg_ids, msg_cnt as usize);
+
     let ffi_context = &*context;
     ffi_context
-        .with_inner(|ctx| message::markseen_msgs(ctx, msg_ids, msg_cnt as usize))
+        .with_inner(|ctx| message::markseen_msgs(ctx, ids))
         .ok();
 }
 
@@ -1267,9 +1276,12 @@ pub unsafe extern "C" fn dc_star_msgs(
         eprintln!("ignoring careless call to dc_star_msgs()");
         return;
     }
+
+    let ids = std::slice::from_raw_parts(msg_ids, msg_cnt as usize);
+
     let ffi_context = &*context;
     ffi_context
-        .with_inner(|ctx| message::star_msgs(ctx, msg_ids, msg_cnt, star))
+        .with_inner(|ctx| message::star_msgs(ctx, ids, star == 1))
         .ok();
 }
 
diff --git a/examples/repl/cmdline.rs b/examples/repl/cmdline.rs
index c45df2d07..12cd9e679 100644
--- a/examples/repl/cmdline.rs
+++ b/examples/repl/cmdline.rs
@@ -899,7 +899,7 @@ pub unsafe fn dc_cmdline(context: &Context, line: &str) -> Result<(), failure::E
             ensure!(!arg1.is_empty(), "Argument <msg-id> missing.");
             let id = arg1.parse()?;
             let res = message::get_msg_info(context, id);
-            println!("{}", as_str(res));
+            println!("{}", res);
         }
         "listfresh" => {
             let msglist = context.get_fresh_msgs();
@@ -922,24 +922,19 @@ pub unsafe fn dc_cmdline(context: &Context, line: &str) -> Result<(), failure::E
             ensure!(!arg1.is_empty(), "Argument <msg-id> missing.");
             let mut msg_ids = [0; 1];
             msg_ids[0] = arg1.parse()?;
-            message::markseen_msgs(context, msg_ids.as_mut_ptr(), 1);
+            message::markseen_msgs(context, &msg_ids);
         }
         "star" | "unstar" => {
             ensure!(!arg1.is_empty(), "Argument <msg-id> missing.");
             let mut msg_ids = [0; 1];
             msg_ids[0] = arg1.parse()?;
-            message::star_msgs(
-                context,
-                msg_ids.as_mut_ptr(),
-                1,
-                if arg0 == "star" { 1 } else { 0 },
-            );
+            message::star_msgs(context, &msg_ids, arg0 == "star");
         }
         "delmsg" => {
             ensure!(!arg1.is_empty(), "Argument <msg-id> missing.");
             let mut ids = [0; 1];
             ids[0] = arg1.parse()?;
-            message::delete_msgs(context, ids.as_mut_ptr(), 1);
+            message::delete_msgs(context, &ids);
         }
         "listcontacts" | "contacts" | "listverified" => {
             let contacts = Contact::get_all(
diff --git a/src/dc_receive_imf.rs b/src/dc_receive_imf.rs
index 2689d2dcc..e2727cb7c 100644
--- a/src/dc_receive_imf.rs
+++ b/src/dc_receive_imf.rs
@@ -351,20 +351,13 @@ unsafe fn add_parts(
     // check, if the mail is already in our database - if so, just update the folder/uid
     // (if the mail was moved around) and finish. (we may get a mail twice eg. if it is
     // moved between folders. make sure, this check is done eg. before securejoin-processing) */
-    let mut old_server_folder = std::ptr::null_mut();
-    let mut old_server_uid = 0;
-
-    if 0 != message::rfc724_mid_exists(
-        context,
-        &rfc724_mid,
-        &mut old_server_folder,
-        &mut old_server_uid,
-    ) {
-        if as_str(old_server_folder) != server_folder.as_ref() || old_server_uid != server_uid {
+    if let Ok((old_server_folder, old_server_uid, _)) =
+        message::rfc724_mid_exists(context, &rfc724_mid)
+    {
+        if old_server_folder != server_folder.as_ref() || old_server_uid != server_uid {
             message::update_server_uid(context, &rfc724_mid, server_folder.as_ref(), server_uid);
         }
 
-        free(old_server_folder.cast());
         cleanup(mime_in_reply_to, mime_references);
         bail!("Message already in DB");
     }
@@ -840,7 +833,7 @@ unsafe fn handle_reports(
                                         let mut chat_id_0 = 0;
                                         let mut msg_id = 0;
 
-                                        if 0 != message::mdn_from_ext(
+                                        if message::mdn_from_ext(
                                             context,
                                             from_id,
                                             as_str(rfc724_mid_0),
diff --git a/src/imap.rs b/src/imap.rs
index dc0e2b8e5..2fde8d25f 100644
--- a/src/imap.rs
+++ b/src/imap.rs
@@ -1,5 +1,4 @@
 use std::net;
-use std::ptr;
 use std::sync::{
     atomic::{AtomicBool, Ordering},
     Arc, Condvar, Mutex, RwLock,
@@ -9,7 +8,6 @@ use std::time::{Duration, SystemTime};
 use crate::constants::*;
 use crate::context::Context;
 use crate::dc_receive_imf::dc_receive_imf;
-use crate::dc_tools::*;
 use crate::events::Event;
 use crate::job::{job_add, Action};
 use crate::login_param::LoginParam;
@@ -822,7 +820,7 @@ impl Imap {
                     .message_id
                     .expect("missing message id");
 
-                if 0 == unsafe { precheck_imf(context, &message_id, folder.as_ref(), cur_uid) } {
+                if !precheck_imf(context, &message_id, folder.as_ref(), cur_uid) {
                     // check passed, go fetch the rest
                     if self.fetch_single_msg(context, &folder, cur_uid) == 0 {
                         info!(
@@ -1641,39 +1639,28 @@ fn get_folder_meaning(folder_name: &imap::types::Name) -> FolderMeaning {
     }
 }
 
-unsafe fn precheck_imf(
-    context: &Context,
-    rfc724_mid: &str,
-    server_folder: &str,
-    server_uid: u32,
-) -> libc::c_int {
-    let mut rfc724_mid_exists: libc::c_int = 0i32;
-    let msg_id: u32;
-    let mut old_server_folder: *mut libc::c_char = ptr::null_mut();
-    let mut old_server_uid: u32 = 0i32 as u32;
-    let mut mark_seen: libc::c_int = 0i32;
-    msg_id = message::rfc724_mid_exists(
-        context,
-        &rfc724_mid,
-        &mut old_server_folder,
-        &mut old_server_uid,
-    );
-    if msg_id != 0i32 as libc::c_uint {
-        rfc724_mid_exists = 1i32;
-        if *old_server_folder.offset(0isize) as libc::c_int == 0i32
-            && old_server_uid == 0i32 as libc::c_uint
-        {
+fn precheck_imf(context: &Context, rfc724_mid: &str, server_folder: &str, server_uid: u32) -> bool {
+    let mut rfc724_mid_exists = false;
+    let mut mark_seen = false;
+
+    if let Ok((old_server_folder, old_server_uid, msg_id)) =
+        message::rfc724_mid_exists(context, &rfc724_mid)
+    {
+        rfc724_mid_exists = true;
+
+        if old_server_folder.is_empty() && old_server_uid == 0 {
             info!(context, "[move] detected bbc-self {}", rfc724_mid,);
-            mark_seen = 1i32
-        } else if as_str(old_server_folder) != server_folder {
+            mark_seen = true;
+        } else if old_server_folder != server_folder {
             info!(context, "[move] detected moved message {}", rfc724_mid,);
             update_msg_move_state(context, &rfc724_mid, MoveState::Stay);
         }
-        if as_str(old_server_folder) != server_folder || old_server_uid != server_uid {
+        if old_server_folder != server_folder || old_server_uid != server_uid {
             update_server_uid(context, &rfc724_mid, server_folder, server_uid);
         }
         context.do_heuristics_moves(server_folder, msg_id);
-        if 0 != mark_seen {
+
+        if mark_seen {
             job_add(
                 context,
                 Action::MarkseenMsgOnImap,
@@ -1683,6 +1670,6 @@ unsafe fn precheck_imf(
             );
         }
     }
-    libc::free(old_server_folder as *mut libc::c_void);
+
     rfc724_mid_exists
 }
diff --git a/src/message.rs b/src/message.rs
index 52872cfdd..6eb9171db 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -1,4 +1,3 @@
-use std::ffi::CString;
 use std::path::{Path, PathBuf};
 use std::ptr;
 
@@ -355,9 +354,9 @@ impl Message {
             if let Some(mut buf) = dc_read_file_safe(context, filename) {
                 unsafe {
                     // just a pointer inside buf, MUST NOT be free()'d
-                    let mut buf_headerline: *const libc::c_char = ptr::null();
+                    let mut buf_headerline = ptr::null();
                     // just a pointer inside buf, MUST NOT be free()'d
-                    let mut buf_setupcodebegin: *const libc::c_char = ptr::null();
+                    let mut buf_setupcodebegin = ptr::null();
 
                     if dc_split_armored_data(
                         buf.as_mut_ptr().cast(),
@@ -534,12 +533,12 @@ impl Lot {
     }
 }
 
-pub unsafe fn get_msg_info(context: &Context, msg_id: u32) -> *mut libc::c_char {
+pub fn get_msg_info(context: &Context, msg_id: u32) -> String {
     let mut ret = String::new();
 
     let msg = Message::load_from_db(context, msg_id);
     if msg.is_err() {
-        return ptr::null_mut();
+        return ret;
     }
 
     let msg = msg.unwrap();
@@ -552,7 +551,7 @@ pub unsafe fn get_msg_info(context: &Context, msg_id: u32) -> *mut libc::c_char
 
     if rawtxt.is_none() {
         ret += &format!("Cannot load message #{}.", msg_id as usize);
-        return ret.strdup();
+        return ret;
     }
     let rawtxt = rawtxt.unwrap();
     let rawtxt = dc_truncate(rawtxt.trim(), 100000, false);
@@ -579,7 +578,7 @@ pub unsafe fn get_msg_info(context: &Context, msg_id: u32) -> *mut libc::c_char
 
     if msg.from_id == 2 || msg.to_id == 2 {
         // device-internal message, no further details needed
-        return ret.strdup();
+        return ret;
     }
 
     if let Ok(rows) = context.sql.query_map(
@@ -671,7 +670,7 @@ pub unsafe fn get_msg_info(context: &Context, msg_id: u32) -> *mut libc::c_char
         }
     }
 
-    ret.strdup()
+    ret
 }
 
 pub fn guess_msgtype_from_suffix(path: &Path) -> Option<(Viewtype, &str)> {
@@ -692,39 +691,27 @@ pub fn guess_msgtype_from_suffix(path: &Path) -> Option<(Viewtype, &str)> {
     KNOWN.get(extension).map(|x| *x)
 }
 
-pub unsafe fn get_mime_headers(context: &Context, msg_id: u32) -> *mut libc::c_char {
-    let headers: Option<String> = context.sql.query_get_value(
+pub fn get_mime_headers(context: &Context, msg_id: u32) -> Option<String> {
+    context.sql.query_get_value(
         context,
         "SELECT mime_headers FROM msgs WHERE id=?;",
         params![msg_id as i32],
-    );
-
-    if let Some(headers) = headers {
-        let h = CString::yolo(headers);
-        dc_strdup_keep_null(h.as_ptr())
-    } else {
-        std::ptr::null_mut()
-    }
+    )
 }
 
-pub unsafe fn delete_msgs(context: &Context, msg_ids: *const u32, msg_cnt: libc::c_int) {
-    if msg_ids.is_null() || msg_cnt <= 0i32 {
-        return;
-    }
-    let mut i: libc::c_int = 0i32;
-    while i < msg_cnt {
-        update_msg_chat_id(context, *msg_ids.offset(i as isize), 3i32 as u32);
+pub fn delete_msgs(context: &Context, msg_ids: &[u32]) {
+    for msg_id in msg_ids.into_iter() {
+        update_msg_chat_id(context, *msg_id, DC_CHAT_ID_TRASH);
         job_add(
             context,
             Action::DeleteMsgOnImap,
-            *msg_ids.offset(i as isize) as libc::c_int,
+            *msg_id as libc::c_int,
             Params::new(),
             0,
         );
-        i += 1
     }
 
-    if 0 != msg_cnt {
+    if !msg_ids.is_empty() {
         context.call_cb(Event::MsgsChanged {
             chat_id: 0,
             msg_id: 0,
@@ -744,17 +731,17 @@ fn update_msg_chat_id(context: &Context, msg_id: u32, chat_id: u32) -> bool {
     .is_ok()
 }
 
-pub fn markseen_msgs(context: &Context, msg_ids: *const u32, msg_cnt: usize) -> bool {
-    if msg_ids.is_null() || msg_cnt <= 0 {
+pub fn markseen_msgs(context: &Context, msg_ids: &[u32]) -> bool {
+    if msg_ids.is_empty() {
         return false;
     }
+
     let msgs = context.sql.prepare(
         "SELECT m.state, c.blocked  FROM msgs m  LEFT JOIN chats c ON c.id=m.chat_id  WHERE m.id=? AND m.chat_id>9",
         |mut stmt, _| {
-            let mut res = Vec::with_capacity(msg_cnt);
-            for i in 0..msg_cnt {
-                let id = unsafe { *msg_ids.offset(i as isize) };
-                let query_res = stmt.query_row(params![id as i32], |row| {
+            let mut res = Vec::with_capacity(msg_ids.len());
+            for id in msg_ids.into_iter() {
+                let query_res = stmt.query_row(params![*id as i32], |row| {
                     Ok((row.get::<_, MessageState>(0)?, row.get::<_, Option<Blocked>>(1)?.unwrap_or_default()))
                 });
                 if let Err(rusqlite::Error::QueryReturnedNoRows) = query_res {
@@ -763,6 +750,7 @@ pub fn markseen_msgs(context: &Context, msg_ids: *const u32, msg_cnt: usize) ->
                 let (state, blocked) = query_res?;
                 res.push((id, state, blocked));
             }
+
             Ok(res)
         }
     );
@@ -777,20 +765,20 @@ pub fn markseen_msgs(context: &Context, msg_ids: *const u32, msg_cnt: usize) ->
     for (id, curr_state, curr_blocked) in msgs.into_iter() {
         if curr_blocked == Blocked::Not {
             if curr_state == MessageState::InFresh || curr_state == MessageState::InNoticed {
-                update_msg_state(context, id, MessageState::InSeen);
+                update_msg_state(context, *id, MessageState::InSeen);
                 info!(context, "Seen message #{}.", id);
 
                 job_add(
                     context,
                     Action::MarkseenMsgOnImap,
-                    id as i32,
+                    *id as i32,
                     Params::new(),
                     0,
                 );
                 send_event = true;
             }
         } else if curr_state == MessageState::InFresh {
-            update_msg_state(context, id, MessageState::InNoticed);
+            update_msg_state(context, *id, MessageState::InNoticed);
             send_event = true;
         }
     }
@@ -815,20 +803,15 @@ pub fn update_msg_state(context: &Context, msg_id: u32, state: MessageState) ->
     .is_ok()
 }
 
-pub fn star_msgs(
-    context: &Context,
-    msg_ids: *const u32,
-    msg_cnt: libc::c_int,
-    star: libc::c_int,
-) -> bool {
-    if msg_ids.is_null() || msg_cnt <= 0 || star != 0 && star != 1 {
+pub fn star_msgs(context: &Context, msg_ids: &[u32], star: bool) -> bool {
+    if msg_ids.is_empty() {
         return false;
     }
     context
         .sql
         .prepare("UPDATE msgs SET starred=? WHERE id=?;", |mut stmt, _| {
-            for i in 0..msg_cnt {
-                stmt.execute(params![star, unsafe { *msg_ids.offset(i as isize) as i32 }])?;
+            for msg_id in msg_ids.into_iter() {
+                stmt.execute(params![star as i32, *msg_id as i32])?;
             }
             Ok(())
         })
@@ -964,26 +947,20 @@ pub fn set_msg_failed(context: &Context, msg_id: u32, error: Option<impl AsRef<s
     }
 }
 
-///returns 1 if an event should be send
-pub unsafe fn mdn_from_ext(
+/// returns true if an event should be send
+pub fn mdn_from_ext(
     context: &Context,
     from_id: u32,
     rfc724_mid: &str,
     timestamp_sent: i64,
-    ret_chat_id: *mut u32,
-    ret_msg_id: *mut u32,
-) -> libc::c_int {
-    if from_id <= 9
-        || rfc724_mid.is_empty()
-        || ret_chat_id.is_null()
-        || ret_msg_id.is_null()
-        || *ret_chat_id != 0
-        || *ret_msg_id != 0
-    {
-        return 0;
+    ret_chat_id: &mut u32,
+    ret_msg_id: &mut u32,
+) -> bool {
+    if from_id <= 9 || rfc724_mid.is_empty() || *ret_chat_id != 0 || *ret_msg_id != 0 {
+        return false;
     }
 
-    let mut read_by_all = 0;
+    let mut read_by_all = false;
 
     if let Ok((msg_id, chat_id, chat_type, msg_state)) = context.sql.query_row(
         "SELECT m.id, c.id, c.type, m.state FROM msgs m  \
@@ -1025,7 +1002,7 @@ pub unsafe fn mdn_from_ext(
             // Normal chat? that's quite easy.
             if chat_type == Chattype::Single {
                 update_msg_state(context, *ret_msg_id, MessageState::OutMdnRcvd);
-                read_by_all = 1;
+                read_by_all = true;
             } else {
                 // send event about new state
                 let ist_cnt: i32 = context
@@ -1052,7 +1029,7 @@ pub unsafe fn mdn_from_ext(
                 let soll_cnt = (chat::get_chat_contact_cnt(context, *ret_chat_id) + 1) / 2;
                 if ist_cnt >= soll_cnt {
                     update_msg_state(context, *ret_msg_id, MessageState::OutMdnRcvd);
-                    read_by_all = 1;
+                    read_by_all = true;
                 } // else wait for more receipts
             }
         }
@@ -1109,40 +1086,23 @@ pub fn rfc724_mid_cnt(context: &Context, rfc724_mid: &str) -> libc::c_int {
     }
 }
 
-pub fn rfc724_mid_exists(
+pub(crate) fn rfc724_mid_exists(
     context: &Context,
     rfc724_mid: &str,
-    ret_server_folder: *mut *mut libc::c_char,
-    ret_server_uid: *mut u32,
-) -> u32 {
-    if rfc724_mid.is_empty() {
-        return 0;
-    }
-    match context.sql.query_row(
+) -> Result<(String, u32, u32), Error> {
+    ensure!(!rfc724_mid.is_empty(), "empty rfc724_mid");
+
+    context.sql.query_row(
         "SELECT server_folder, server_uid, id FROM msgs WHERE rfc724_mid=?",
         &[rfc724_mid],
         |row| {
-            if !ret_server_folder.is_null() {
-                unsafe { *ret_server_folder = row.get::<_, String>(0)?.strdup() };
-            }
-            if !ret_server_uid.is_null() {
-                unsafe { *ret_server_uid = row.get(1)? };
-            }
-            row.get(2)
-        },
-    ) {
-        Ok(res) => res,
-        Err(_err) => {
-            if !ret_server_folder.is_null() {
-                unsafe { *ret_server_folder = ptr::null_mut() };
-            }
-            if !ret_server_uid.is_null() {
-                unsafe { *ret_server_uid = 0 };
-            }
+            let server_folder = row.get::<_, Option<String>>(0)?.unwrap_or_default();
+            let server_uid = row.get(1)?;
+            let msg_id = row.get(2)?;
 
-            0
-        }
-    }
+            Ok((server_folder, server_uid, msg_id))
+        },
+    )
 }
 
 pub fn update_server_uid(