diff --git a/server/autolinkplugin/plugin.go b/server/autolinkplugin/plugin.go
index c338e545..1980fba8 100644
--- a/server/autolinkplugin/plugin.go
+++ b/server/autolinkplugin/plugin.go
@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"strings"
 	"sync"
+	"unicode/utf8"
 
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/plugin"
@@ -208,6 +209,11 @@ func (p *Plugin) ProcessPost(c *plugin.Context, post *model.Post) (*model.Post,
 			return nil, ""
 		}
 
+		if runes := utf8.RuneCountInString(postText); runes > model.POST_MESSAGE_MAX_RUNES_V1 {
+			p.API.LogWarn("Rewritten message would be too long, skipping", "rewrittenLength", runes)
+			return nil, ""
+		}
+
 		post.Message = postText
 	}
 
@@ -235,5 +241,11 @@ func (p *Plugin) MessageWillBeUpdated(c *plugin.Context, post *model.Post, _ *mo
 		return post, ""
 	}
 
-	return p.ProcessPost(c, post)
+	modifiedPost, reason := p.ProcessPost(c, post)
+
+	if modifiedPost == nil && reason == "" {
+		return post, ""
+	}
+
+	return modifiedPost, reason
 }
diff --git a/server/autolinkplugin/plugin_test.go b/server/autolinkplugin/plugin_test.go
index 5aa8d81a..b1699dc3 100644
--- a/server/autolinkplugin/plugin_test.go
+++ b/server/autolinkplugin/plugin_test.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"github.com/mattermost/mattermost-server/v5/model"
@@ -305,6 +306,9 @@ func TestSpecialCases(t *testing.T) {
 		Pattern:  "(example)",
 		Template: "test",
 		Scope:    []string{"other-team/town-square"},
+	}, autolink.Autolink{
+		Pattern:  "(toolong)",
+		Template: strings.Repeat("1", model.POST_MESSAGE_MAX_RUNES_V1+1),
 	})
 	validConfig := Config{
 		EnableAdminCommand: false,
@@ -331,6 +335,8 @@ func TestSpecialCases(t *testing.T) {
 	api.On("GetChannel", mock.AnythingOfType("string")).Return(&testChannel, nil)
 	api.On("GetTeam", mock.AnythingOfType("string")).Return(&testTeam, nil)
 
+	api.On("LogWarn", mock.AnythingOfType("string"), mock.AnythingOfType("string"), mock.AnythingOfType("int"))
+
 	testUser := model.User{
 		IsBot: false,
 	}
@@ -344,115 +350,156 @@ func TestSpecialCases(t *testing.T) {
 	var tests = []struct {
 		inputMessage    string
 		expectedMessage string
+		expectedIgnored bool
 	}{
 		{
 			"hello ``` Mattermost ``` goodbye",
 			"hello ``` Mattermost ``` goodbye",
+			false,
 		}, {
 			"hello\n```\nMattermost\n```\ngoodbye",
 			"hello\n```\nMattermost\n```\ngoodbye",
+			false,
 		}, {
 			"Mattermost ``` Mattermost ``` goodbye",
 			"[Mattermost](https://mattermost.com) ``` Mattermost ``` goodbye",
+			false,
 		}, {
 			"``` Mattermost ``` Mattermost",
 			"``` Mattermost ``` [Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"Mattermost ``` Mattermost ```",
 			"[Mattermost](https://mattermost.com) ``` Mattermost ```",
+			false,
 		}, {
 			"Mattermost ``` Mattermost ```\n\n",
 			"[Mattermost](https://mattermost.com) ``` Mattermost ```\n\n",
+			false,
 		}, {
 			"hello ` Mattermost ` goodbye",
 			"hello ` Mattermost ` goodbye",
+			false,
 		}, {
 			"hello\n`\nMattermost\n`\ngoodbye",
 			"hello\n`\nMattermost\n`\ngoodbye",
+			false,
 		}, {
 			"Mattermost ` Mattermost ` goodbye",
 			"[Mattermost](https://mattermost.com) ` Mattermost ` goodbye",
+			false,
 		}, {
 			"` Mattermost ` Mattermost",
 			"` Mattermost ` [Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"Mattermost ` Mattermost `",
 			"[Mattermost](https://mattermost.com) ` Mattermost `",
+			false,
 		}, {
 			"Mattermost ` Mattermost `\n\n",
 			"[Mattermost](https://mattermost.com) ` Mattermost `\n\n",
+			false,
 		}, {
 			"hello ``` Mattermost ``` goodbye ` Mattermost ` end",
 			"hello ``` Mattermost ``` goodbye ` Mattermost ` end",
+			false,
 		}, {
 			"hello\n```\nMattermost\n```\ngoodbye ` Mattermost ` end",
 			"hello\n```\nMattermost\n```\ngoodbye ` Mattermost ` end",
+			false,
 		}, {
 			"Mattermost ``` Mattermost ``` goodbye ` Mattermost ` end",
 			"[Mattermost](https://mattermost.com) ``` Mattermost ``` goodbye ` Mattermost ` end",
+			false,
 		}, {
 			"``` Mattermost ``` Mattermost",
 			"``` Mattermost ``` [Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"```\n` Mattermost `\n```\nMattermost",
 			"```\n` Mattermost `\n```\n[Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"  Mattermost",
 			"  [Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"    Mattermost",
 			"    Mattermost",
+			false,
 		}, {
 			"    ```\nMattermost\n    ```",
 			"    ```\n[Mattermost](https://mattermost.com)\n    ```",
+			false,
 		}, {
 			"` ``` `\nMattermost\n` ``` `",
 			"` ``` `\n[Mattermost](https://mattermost.com)\n` ``` `",
+			false,
 		}, {
 			"Mattermost \n Mattermost",
 			"[Mattermost](https://mattermost.com) \n [Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"[Mattermost](https://mattermost.com)",
 			"[Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"[  Mattermost  ](https://mattermost.com)",
 			"[  Mattermost  ](https://mattermost.com)",
+			false,
 		}, {
 			"[  Mattermost  ][1]\n\n[1]: https://mattermost.com",
 			"[  Mattermost  ][1]\n\n[1]: https://mattermost.com",
+			false,
 		}, {
 			"![  Mattermost  ](https://mattermost.com/example.png)",
 			"![  Mattermost  ](https://mattermost.com/example.png)",
+			false,
 		}, {
 			"![  Mattermost  ][1]\n\n[1]: https://mattermost.com/example.png",
 			"![  Mattermost  ][1]\n\n[1]: https://mattermost.com/example.png",
+			false,
 		}, {
 			"foo!bar\nExample\nfoo!bar Mattermost",
 			"fb\n[Example](https://example.com)\nfb [Mattermost](https://mattermost.com)",
+			false,
 		}, {
 			"foo!bar",
 			"fb",
+			false,
 		}, {
 			"foo!barfoo!bar",
 			"foo!barfoo!bar",
+			false,
 		}, {
 			"foo!bar & foo!bar",
 			"fb & fb",
+			false,
 		}, {
 			"foo!bar & foo!bar\nfoo!bar & foo!bar\nfoo!bar & foo!bar",
 			"fb & fb\nfb & fb\nfb & fb",
+			false,
 		}, {
 			"https://mattermost.atlassian.net/browse/MM-12345",
 			"[MM-12345](https://mattermost.atlassian.net/browse/MM-12345)",
+			false,
 		}, {
 			"Welcome https://mattermost.atlassian.net/browse/MM-12345",
 			"Welcome [MM-12345](https://mattermost.atlassian.net/browse/MM-12345)",
+			false,
 		}, {
 			"text https://mattermost.atlassian.net/browse/MM-12345 other text",
 			"text [MM-12345](https://mattermost.atlassian.net/browse/MM-12345) other text",
+			false,
 		}, {
 			"check out MM-12345 too",
 			"check out [MM-12345](https://mattermost.atlassian.net/browse/MM-12345) too",
+			false,
+		}, {
+			"toolong",
+			"toolong",
+			true,
 		},
 	}
 
@@ -465,9 +512,15 @@ func TestSpecialCases(t *testing.T) {
 					Message: tt.inputMessage,
 				}
 
-				rpost, _ := p.MessageWillBePosted(&plugin.Context{}, post)
+				rpost, err := p.MessageWillBePosted(&plugin.Context{}, post)
 
-				assert.Equal(t, tt.expectedMessage, rpost.Message)
+				if tt.expectedIgnored {
+					assert.Nil(t, rpost)
+				} else {
+					assert.Equal(t, tt.expectedMessage, rpost.Message)
+				}
+
+				assert.Equal(t, "", err)
 			}
 			{
 				// user updates the modified post but with no changes
@@ -476,9 +529,15 @@ func TestSpecialCases(t *testing.T) {
 					Message: tt.expectedMessage,
 				}
 
-				rpost, _ := p.MessageWillBeUpdated(&plugin.Context{}, post, post)
+				rpost, err := p.MessageWillBeUpdated(&plugin.Context{}, post, post)
 
-				assert.Equal(t, tt.expectedMessage, rpost.Message)
+				if tt.expectedIgnored {
+					assert.Same(t, post, rpost)
+				} else {
+					assert.Equal(t, tt.expectedMessage, rpost.Message)
+				}
+
+				assert.Equal(t, "", err)
 			}
 			{
 				// user updates the modified post and sets it back to the original text
@@ -490,9 +549,15 @@ func TestSpecialCases(t *testing.T) {
 					Message: tt.inputMessage,
 				}
 
-				rpost, _ := p.MessageWillBeUpdated(&plugin.Context{}, originalPost, post)
+				rpost, err := p.MessageWillBeUpdated(&plugin.Context{}, originalPost, post)
+
+				if tt.expectedIgnored {
+					assert.Same(t, originalPost, rpost)
+				} else {
+					assert.Equal(t, tt.expectedMessage, rpost.Message)
+				}
 
-				assert.Equal(t, tt.expectedMessage, rpost.Message)
+				assert.Equal(t, "", err)
 			}
 			{
 				// user updates an empty post to the original text
@@ -502,9 +567,15 @@ func TestSpecialCases(t *testing.T) {
 					Message: tt.inputMessage,
 				}
 
-				rpost, _ := p.MessageWillBeUpdated(&plugin.Context{}, post, emptyPost)
+				rpost, err := p.MessageWillBeUpdated(&plugin.Context{}, post, emptyPost)
+
+				if tt.expectedIgnored {
+					assert.Same(t, post, rpost)
+				} else {
+					assert.Equal(t, tt.expectedMessage, rpost.Message)
+				}
 
-				assert.Equal(t, tt.expectedMessage, rpost.Message)
+				assert.Equal(t, "", err)
 			}
 		})
 	}