diff --git a/pkg/pmapi/client.go b/pkg/pmapi/client.go
index 6e41879..d99ab48 100644
--- a/pkg/pmapi/client.go
+++ b/pkg/pmapi/client.go
@@ -43,9 +43,7 @@ const Version = 3
 
 // API return codes.
 const (
-	ForceUpgradeBadAPIVersion = 5003
-	ForceUpgradeInvalidAPI    = 5004
-	ForceUpgradeBadAppVersion = 5005
+	ForceUpgradeBadAppVersion = 5003
 	APIOffline                = 7001
 	ImportMessageTooLong      = 36022
 	BansRequests              = 85131
diff --git a/pkg/pmapi/res.go b/pkg/pmapi/res.go
index 298f6c0..52b554e 100644
--- a/pkg/pmapi/res.go
+++ b/pkg/pmapi/res.go
@@ -41,22 +41,20 @@ type Res struct {
 
 // Err returns error if the response is an error. Otherwise, returns nil.
 func (res Res) Err() error {
-	if res.StatusCode == http.StatusUnprocessableEntity {
-		return &ErrUnprocessableEntity{errors.New(res.Error)}
+	if res.Code == ForceUpgradeBadAppVersion {
+		return ErrUpgradeApplication
 	}
 
-	if res.ResError == nil {
-		return nil
+	if res.Code == APIOffline {
+		return ErrAPINotReachable
 	}
 
-	if res.Code == ForceUpgradeBadAPIVersion ||
-		res.Code == ForceUpgradeInvalidAPI ||
-		res.Code == ForceUpgradeBadAppVersion {
-		return ErrUpgradeApplication
+	if res.StatusCode == http.StatusUnprocessableEntity {
+		return &ErrUnprocessableEntity{errors.New(res.Error)}
 	}
 
-	if res.Code == APIOffline {
-		return ErrAPINotReachable
+	if res.ResError == nil {
+		return nil
 	}
 
 	return &Error{
diff --git a/unreleased.md b/unreleased.md
index 88bc730..6aba92e 100644
--- a/unreleased.md
+++ b/unreleased.md
@@ -58,3 +58,4 @@ Changelog [format](http://keepachangelog.com/en/1.0.0/)
 ### Fixed
 * GODT-900 Remove \Deleted flag after re-importing the message (do not delete messages by moving to local folder and back).
 * GODT-908 Do not unpause event loop if other mailbox is still fetching.
+* Check deprecated status code first to better determine API error.