diff --git a/src/imap.rs b/src/imap.rs
index ec6addb9b..ff1c32b0e 100644
--- a/src/imap.rs
+++ b/src/imap.rs
@@ -11,7 +11,7 @@ use crate::dc_receive_imf::dc_receive_imf;
 use crate::error::Error;
 use crate::events::Event;
 use crate::job::{connect_to_inbox, job_add, Action};
-use crate::login_param::{CertificateChecks, LoginParam};
+use crate::login_param::{dc_build_tls, CertificateChecks, LoginParam};
 use crate::message::{self, update_msg_move_state, update_server_uid};
 use crate::oauth2::dc_get_oauth2_access_token;
 use crate::param::Params;
@@ -111,25 +111,7 @@ impl Client {
         certificate_checks: CertificateChecks,
     ) -> imap::error::Result<Self> {
         let stream = net::TcpStream::connect(addr)?;
-        let mut tls_builder = native_tls::TlsConnector::builder();
-        let tls = match certificate_checks {
-            CertificateChecks::Automatic => {
-                // Same as AcceptInvalidCertificates for now.
-                // TODO: use provider database when it becomes available
-                tls_builder
-                    .danger_accept_invalid_hostnames(true)
-                    .danger_accept_invalid_certs(true)
-            }
-            CertificateChecks::Strict => &mut tls_builder,
-            CertificateChecks::AcceptInvalidHostnames => {
-                tls_builder.danger_accept_invalid_hostnames(true)
-            }
-            CertificateChecks::AcceptInvalidCertificates => tls_builder
-                .danger_accept_invalid_hostnames(true)
-                .danger_accept_invalid_certs(true),
-        }
-        .build()
-        .unwrap();
+        let tls = dc_build_tls(certificate_checks).unwrap();
 
         let s = stream.try_clone().expect("cloning the stream failed");
         let tls_stream = native_tls::TlsConnector::connect(&tls, domain.as_ref(), s)?;
diff --git a/src/login_param.rs b/src/login_param.rs
index 3fc64031f..01e85b32a 100644
--- a/src/login_param.rs
+++ b/src/login_param.rs
@@ -251,6 +251,29 @@ fn get_readable_flags(flags: i32) -> String {
     res
 }
 
+pub fn dc_build_tls(
+    certificate_checks: CertificateChecks,
+) -> Result<native_tls::TlsConnector, native_tls::Error> {
+    let mut tls_builder = native_tls::TlsConnector::builder();
+    match certificate_checks {
+        CertificateChecks::Automatic => {
+            // Same as AcceptInvalidCertificates for now.
+            // TODO: use provider database when it becomes available
+            tls_builder
+                .danger_accept_invalid_hostnames(true)
+                .danger_accept_invalid_certs(true)
+        }
+        CertificateChecks::Strict => &mut tls_builder,
+        CertificateChecks::AcceptInvalidHostnames => {
+            tls_builder.danger_accept_invalid_hostnames(true)
+        }
+        CertificateChecks::AcceptInvalidCertificates => tls_builder
+            .danger_accept_invalid_hostnames(true)
+            .danger_accept_invalid_certs(true),
+    }
+    .build()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/src/smtp.rs b/src/smtp.rs
index 4e8e30d6d..089607bc8 100644
--- a/src/smtp.rs
+++ b/src/smtp.rs
@@ -5,7 +5,7 @@ use crate::constants::*;
 use crate::context::Context;
 use crate::error::Error;
 use crate::events::Event;
-use crate::login_param::{CertificateChecks, LoginParam};
+use crate::login_param::{dc_build_tls, LoginParam};
 use crate::oauth2::*;
 
 #[derive(DebugStub)]
@@ -68,26 +68,7 @@ impl Smtp {
         let domain = &lp.send_server;
         let port = lp.send_port as u16;
 
-        let mut tls_builder = native_tls::TlsConnector::builder();
-        let tls = match lp.smtp_certificate_checks {
-            CertificateChecks::Automatic => {
-                // Same as AcceptInvalidCertificates for now.
-                // TODO: use provider database when it becomes available
-                tls_builder
-                    .danger_accept_invalid_hostnames(true)
-                    .danger_accept_invalid_certs(true)
-            }
-            CertificateChecks::Strict => &mut tls_builder,
-            CertificateChecks::AcceptInvalidHostnames => {
-                tls_builder.danger_accept_invalid_hostnames(true)
-            }
-            CertificateChecks::AcceptInvalidCertificates => tls_builder
-                .danger_accept_invalid_hostnames(true)
-                .danger_accept_invalid_certs(true),
-        }
-        .build()
-        .unwrap();
-
+        let tls = dc_build_tls(lp.smtp_certificate_checks).unwrap();
         let tls_parameters = ClientTlsParameters::new(domain.to_string(), tls);
 
         let creds = if 0 != lp.server_flags & (DC_LP_AUTH_OAUTH2 as i32) {