diff --git a/lib/smtp.c b/lib/smtp.c
index 4c12a102b..334814a8a 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -105,6 +105,10 @@ static CURLcode smtp_setup_connection(struct connectdata *conn);
 static CURLcode smtp_parse_url_options(struct connectdata *conn);
 static CURLcode smtp_parse_url_path(struct connectdata *conn);
 static CURLcode smtp_parse_custom_request(struct connectdata *conn);
+static CURLcode smtp_calc_sasl_details(struct connectdata *conn,
+                                       const char **mech,
+                                       char **initresp, size_t *len,
+                                       smtpstate *state1, smtpstate *state2);
 
 /*
  * SMTP protocol handler.
@@ -471,7 +475,6 @@ static CURLcode smtp_perform_auth(struct connectdata *conn,
 static CURLcode smtp_perform_authentication(struct connectdata *conn)
 {
   CURLcode result = CURLE_OK;
-  struct SessionHandle *data = conn->data;
   struct smtp_conn *smtpc = &conn->proto.smtpc;
   const char *mech = NULL;
   char *initresp = NULL;
@@ -487,73 +490,9 @@ static CURLcode smtp_perform_authentication(struct connectdata *conn)
     return result;
   }
 
-  /* Calculate the supported authentication mechanism, by decreasing order of
-     security, as well as the initial response where appropriate */
-#ifndef CURL_DISABLE_CRYPTO_AUTH
-  if((smtpc->authmechs & SASL_MECH_DIGEST_MD5) &&
-     (smtpc->prefmech & SASL_MECH_DIGEST_MD5)) {
-    mech = SASL_MECH_STRING_DIGEST_MD5;
-    state1 = SMTP_AUTH_DIGESTMD5;
-    smtpc->authused = SASL_MECH_DIGEST_MD5;
-  }
-  else if((smtpc->authmechs & SASL_MECH_CRAM_MD5) &&
-          (smtpc->prefmech & SASL_MECH_CRAM_MD5)) {
-    mech = SASL_MECH_STRING_CRAM_MD5;
-    state1 = SMTP_AUTH_CRAMMD5;
-    smtpc->authused = SASL_MECH_CRAM_MD5;
-  }
-  else
-#endif
-#ifdef USE_NTLM
-  if((smtpc->authmechs & SASL_MECH_NTLM) &&
-     (smtpc->prefmech & SASL_MECH_NTLM)) {
-    mech = SASL_MECH_STRING_NTLM;
-    state1 = SMTP_AUTH_NTLM;
-    state2 = SMTP_AUTH_NTLM_TYPE2MSG;
-    smtpc->authused = SASL_MECH_NTLM;
-
-    if(data->set.sasl_ir)
-      result = Curl_sasl_create_ntlm_type1_message(conn->user, conn->passwd,
-                                                   &conn->ntlm,
-                                                   &initresp, &len);
-    }
-  else
-#endif
-  if(((smtpc->authmechs & SASL_MECH_XOAUTH2) &&
-      (smtpc->prefmech & SASL_MECH_XOAUTH2) &&
-      (smtpc->prefmech != SASL_AUTH_ANY)) || conn->xoauth2_bearer) {
-    mech = SASL_MECH_STRING_XOAUTH2;
-    state1 = SMTP_AUTH_XOAUTH2;
-    state2 = SMTP_AUTH_FINAL;
-    smtpc->authused = SASL_MECH_XOAUTH2;
-
-    if(data->set.sasl_ir)
-      result = Curl_sasl_create_xoauth2_message(conn->data, conn->user,
-                                                conn->xoauth2_bearer,
-                                                &initresp, &len);
-  }
-  else if((smtpc->authmechs & SASL_MECH_LOGIN) &&
-     (smtpc->prefmech & SASL_MECH_LOGIN)) {
-    mech = SASL_MECH_STRING_LOGIN;
-    state1 = SMTP_AUTH_LOGIN;
-    state2 = SMTP_AUTH_LOGIN_PASSWD;
-    smtpc->authused = SASL_MECH_LOGIN;
-
-    if(data->set.sasl_ir)
-      result = Curl_sasl_create_login_message(conn->data, conn->user,
-                                              &initresp, &len);
-  }
-  else if((smtpc->authmechs & SASL_MECH_PLAIN) &&
-          (smtpc->prefmech & SASL_MECH_PLAIN)) {
-    mech = SASL_MECH_STRING_PLAIN;
-    state1 = SMTP_AUTH_PLAIN;
-    state2 = SMTP_AUTH_FINAL;
-    smtpc->authused = SASL_MECH_PLAIN;
-
-    if(data->set.sasl_ir)
-      result = Curl_sasl_create_plain_message(conn->data, conn->user,
-                                              conn->passwd, &initresp, &len);
-  }
+  /* Calculate the SASL login details */
+  result = smtp_calc_sasl_details(conn, &mech, &initresp, &len, &state1,
+                                  &state2);
 
   if(!result) {
     if(mech) {
@@ -2044,6 +1983,91 @@ static CURLcode smtp_parse_custom_request(struct connectdata *conn)
   return result;
 }
 
+/***********************************************************************
+ *
+ * smtp_calc_sasl_details()
+ *
+ * Calculate the required login details for SASL authentication.
+ */
+static CURLcode smtp_calc_sasl_details(struct connectdata *conn,
+                                       const char **mech,
+                                       char **initresp, size_t *len,
+                                       smtpstate *state1, smtpstate *state2)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct smtp_conn *smtpc = &conn->proto.smtpc;
+
+  /* Calculate the supported authentication mechanism, by decreasing order of
+     security, as well as the initial response where appropriate */
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+  if((smtpc->authmechs & SASL_MECH_DIGEST_MD5) &&
+     (smtpc->prefmech & SASL_MECH_DIGEST_MD5)) {
+    *mech = SASL_MECH_STRING_DIGEST_MD5;
+    *state1 = SMTP_AUTH_DIGESTMD5;
+    smtpc->authused = SASL_MECH_DIGEST_MD5;
+  }
+  else if((smtpc->authmechs & SASL_MECH_CRAM_MD5) &&
+          (smtpc->prefmech & SASL_MECH_CRAM_MD5)) {
+    *mech = SASL_MECH_STRING_CRAM_MD5;
+    *state1 = SMTP_AUTH_CRAMMD5;
+    smtpc->authused = SASL_MECH_CRAM_MD5;
+  }
+  else
+#endif
+#ifdef USE_NTLM
+  if((smtpc->authmechs & SASL_MECH_NTLM) &&
+     (smtpc->prefmech & SASL_MECH_NTLM)) {
+    *mech = SASL_MECH_STRING_NTLM;
+    *state1 = SMTP_AUTH_NTLM;
+    *state2 = SMTP_AUTH_NTLM_TYPE2MSG;
+    smtpc->authused = SASL_MECH_NTLM;
+
+    if(data->set.sasl_ir)
+      result = Curl_sasl_create_ntlm_type1_message(conn->user, conn->passwd,
+                                                   &conn->ntlm,
+                                                   initresp, len);
+    }
+  else
+#endif
+  if(((smtpc->authmechs & SASL_MECH_XOAUTH2) &&
+      (smtpc->prefmech & SASL_MECH_XOAUTH2) &&
+      (smtpc->prefmech != SASL_AUTH_ANY)) || conn->xoauth2_bearer) {
+    *mech = SASL_MECH_STRING_XOAUTH2;
+    *state1 = SMTP_AUTH_XOAUTH2;
+    *state2 = SMTP_AUTH_FINAL;
+    smtpc->authused = SASL_MECH_XOAUTH2;
+
+    if(data->set.sasl_ir)
+      result = Curl_sasl_create_xoauth2_message(data, conn->user,
+                                                conn->xoauth2_bearer,
+                                                initresp, len);
+  }
+  else if((smtpc->authmechs & SASL_MECH_LOGIN) &&
+          (smtpc->prefmech & SASL_MECH_LOGIN)) {
+    *mech = SASL_MECH_STRING_LOGIN;
+    *state1 = SMTP_AUTH_LOGIN;
+    *state2 = SMTP_AUTH_LOGIN_PASSWD;
+    smtpc->authused = SASL_MECH_LOGIN;
+
+    if(data->set.sasl_ir)
+      result = Curl_sasl_create_login_message(data, conn->user, initresp, len);
+  }
+  else if((smtpc->authmechs & SASL_MECH_PLAIN) &&
+          (smtpc->prefmech & SASL_MECH_PLAIN)) {
+    *mech = SASL_MECH_STRING_PLAIN;
+    *state1 = SMTP_AUTH_PLAIN;
+    *state2 = SMTP_AUTH_FINAL;
+    smtpc->authused = SASL_MECH_PLAIN;
+
+    if(data->set.sasl_ir)
+      result = Curl_sasl_create_plain_message(data, conn->user, conn->passwd,
+                                              initresp, len);
+  }
+
+  return result;
+}
+
 CURLcode Curl_smtp_escape_eob(struct connectdata *conn, ssize_t nread)
 {
   /* When sending a SMTP payload we must detect CRLF. sequences making sure