diff --git a/modules/markup/html.go b/modules/markup/html.go
index 56e1a1c54eda..21bd6206e0eb 100644
--- a/modules/markup/html.go
+++ b/modules/markup/html.go
@@ -609,7 +609,7 @@ func mentionProcessor(ctx *RenderContext, node *html.Node) {
 		if ok && strings.Contains(mention, "/") {
 			mentionOrgAndTeam := strings.Split(mention, "/")
 			if mentionOrgAndTeam[0][1:] == ctx.Metas["org"] && strings.Contains(teams, ","+strings.ToLower(mentionOrgAndTeam[1])+",") {
-				replaceContent(node, loc.Start, loc.End, createLink(util.URLJoin(setting.AppURL, "org", ctx.Metas["org"], "teams", mentionOrgAndTeam[1]), mention, "mention"))
+				replaceContent(node, loc.Start, loc.End, createLink(util.URLJoin(ctx.Links.Prefix(), "org", ctx.Metas["org"], "teams", mentionOrgAndTeam[1]), mention, "mention"))
 				node = node.NextSibling.NextSibling
 				start = 0
 				continue
@@ -620,7 +620,7 @@ func mentionProcessor(ctx *RenderContext, node *html.Node) {
 		mentionedUsername := mention[1:]
 
 		if DefaultProcessorHelper.IsUsernameMentionable != nil && DefaultProcessorHelper.IsUsernameMentionable(ctx.Ctx, mentionedUsername) {
-			replaceContent(node, loc.Start, loc.End, createLink(util.URLJoin(setting.AppURL, mentionedUsername), mention, "mention"))
+			replaceContent(node, loc.Start, loc.End, createLink(util.URLJoin(ctx.Links.Prefix(), mentionedUsername), mention, "mention"))
 			node = node.NextSibling.NextSibling
 		} else {
 			node = node.NextSibling
@@ -898,9 +898,9 @@ func issueIndexPatternProcessor(ctx *RenderContext, node *html.Node) {
 				path = "pulls"
 			}
 			if ref.Owner == "" {
-				link = createLink(util.URLJoin(setting.AppURL, ctx.Metas["user"], ctx.Metas["repo"], path, ref.Issue), reftext, "ref-issue")
+				link = createLink(util.URLJoin(ctx.Links.Prefix(), ctx.Metas["user"], ctx.Metas["repo"], path, ref.Issue), reftext, "ref-issue")
 			} else {
-				link = createLink(util.URLJoin(setting.AppURL, ref.Owner, ref.Name, path, ref.Issue), reftext, "ref-issue")
+				link = createLink(util.URLJoin(ctx.Links.Prefix(), ref.Owner, ref.Name, path, ref.Issue), reftext, "ref-issue")
 			}
 		}
 
@@ -939,7 +939,7 @@ func commitCrossReferencePatternProcessor(ctx *RenderContext, node *html.Node) {
 		}
 
 		reftext := ref.Owner + "/" + ref.Name + "@" + base.ShortSha(ref.CommitSha)
-		link := createLink(util.URLJoin(setting.AppSubURL, ref.Owner, ref.Name, "commit", ref.CommitSha), reftext, "commit")
+		link := createLink(util.URLJoin(ctx.Links.Prefix(), ref.Owner, ref.Name, "commit", ref.CommitSha), reftext, "commit")
 
 		replaceContent(node, ref.RefLocation.Start, ref.RefLocation.End, link)
 		node = node.NextSibling.NextSibling
@@ -1166,7 +1166,7 @@ func hashCurrentPatternProcessor(ctx *RenderContext, node *html.Node) {
 			continue
 		}
 
-		link := util.URLJoin(setting.AppURL, ctx.Metas["user"], ctx.Metas["repo"], "commit", hash)
+		link := util.URLJoin(ctx.Links.Prefix(), ctx.Metas["user"], ctx.Metas["repo"], "commit", hash)
 		replaceContent(node, m[2], m[3], createCodeLink(link, base.ShortSha(hash), "commit"))
 		start = 0
 		node = node.NextSibling.NextSibling
diff --git a/modules/markup/html_internal_test.go b/modules/markup/html_internal_test.go
index 93ba9d7667c4..e313be7040c7 100644
--- a/modules/markup/html_internal_test.go
+++ b/modules/markup/html_internal_test.go
@@ -287,6 +287,7 @@ func TestRender_IssueIndexPattern_Document(t *testing.T) {
 }
 
 func testRenderIssueIndexPattern(t *testing.T, input, expected string, ctx *RenderContext) {
+	ctx.Links.AbsolutePrefix = true
 	if ctx.Links.Base == "" {
 		ctx.Links.Base = TestRepoURL
 	}
diff --git a/modules/markup/html_test.go b/modules/markup/html_test.go
index ccb63c6baba8..55de65d196dc 100644
--- a/modules/markup/html_test.go
+++ b/modules/markup/html_test.go
@@ -43,7 +43,8 @@ func TestRender_Commits(t *testing.T) {
 			Ctx:          git.DefaultContext,
 			RelativePath: ".md",
 			Links: markup.Links{
-				Base: markup.TestRepoURL,
+				AbsolutePrefix: true,
+				Base:           markup.TestRepoURL,
 			},
 			Metas: localMetas,
 		}, input)
@@ -96,7 +97,8 @@ func TestRender_CrossReferences(t *testing.T) {
 			Ctx:          git.DefaultContext,
 			RelativePath: "a.md",
 			Links: markup.Links{
-				Base: setting.AppSubURL,
+				AbsolutePrefix: true,
+				Base:           setting.AppSubURL,
 			},
 			Metas: localMetas,
 		}, input)
@@ -588,7 +590,8 @@ func TestPostProcess_RenderDocument(t *testing.T) {
 		err := markup.PostProcess(&markup.RenderContext{
 			Ctx: git.DefaultContext,
 			Links: markup.Links{
-				Base: "https://example.com",
+				AbsolutePrefix: true,
+				Base:           "https://example.com",
 			},
 			Metas: localMetas,
 		}, strings.NewReader(input), &res)
diff --git a/modules/markup/markdown/markdown_test.go b/modules/markup/markdown/markdown_test.go
index dbf95e5e625d..a12bd4f9e7c2 100644
--- a/modules/markup/markdown/markdown_test.go
+++ b/modules/markup/markdown/markdown_test.go
@@ -130,11 +130,11 @@ func testAnswers(baseURLContent, baseURLImages string) []string {
 <li><a href="` + baseURLContent + `/Links" rel="nofollow">Links, Language bindings, Engine bindings</a></li>
 <li><a href="` + baseURLContent + `/Tips" rel="nofollow">Tips</a></li>
 </ul>
-<p>See commit <a href="http://localhost:3000/gogits/gogs/commit/65f1bf27bc" rel="nofollow"><code>65f1bf27bc</code></a></p>
+<p>See commit <a href="/gogits/gogs/commit/65f1bf27bc" rel="nofollow"><code>65f1bf27bc</code></a></p>
 <p>Ideas and codes</p>
 <ul>
-<li>Bezier widget (by <a href="` + AppURL + `r-lyeh" rel="nofollow">@r-lyeh</a>) <a href="http://localhost:3000/ocornut/imgui/issues/786" class="ref-issue" rel="nofollow">ocornut/imgui#786</a></li>
-<li>Bezier widget (by <a href="` + AppURL + `r-lyeh" rel="nofollow">@r-lyeh</a>) <a href="http://localhost:3000/gogits/gogs/issues/786" class="ref-issue" rel="nofollow">#786</a></li>
+<li>Bezier widget (by <a href="/r-lyeh" rel="nofollow">@r-lyeh</a>) <a href="http://localhost:3000/ocornut/imgui/issues/786" class="ref-issue" rel="nofollow">ocornut/imgui#786</a></li>
+<li>Bezier widget (by <a href="/r-lyeh" rel="nofollow">@r-lyeh</a>) <a href="http://localhost:3000/gogits/gogs/issues/786" class="ref-issue" rel="nofollow">#786</a></li>
 <li>Node graph editors <a href="https://github.com/ocornut/imgui/issues/306" rel="nofollow">https://github.com/ocornut/imgui/issues/306</a></li>
 <li><a href="` + baseURLContent + `/memory_editor_example" rel="nofollow">Memory Editor</a></li>
 <li><a href="` + baseURLContent + `/plot_var_example" rel="nofollow">Plot var helper</a></li>
diff --git a/modules/markup/renderer.go b/modules/markup/renderer.go
index 5a7adcc55322..0f0bf557403e 100644
--- a/modules/markup/renderer.go
+++ b/modules/markup/renderer.go
@@ -82,9 +82,17 @@ type RenderContext struct {
 }
 
 type Links struct {
-	Base       string
-	BranchPath string
-	TreePath   string
+	AbsolutePrefix bool
+	Base           string
+	BranchPath     string
+	TreePath       string
+}
+
+func (l *Links) Prefix() string {
+	if l.AbsolutePrefix {
+		return setting.AppURL
+	}
+	return setting.AppSubURL
 }
 
 func (l *Links) HasBranchInfo() bool {
diff --git a/modules/templates/util_render_test.go b/modules/templates/util_render_test.go
index 8648967d3861..15aee8912d1e 100644
--- a/modules/templates/util_render_test.go
+++ b/modules/templates/util_render_test.go
@@ -117,21 +117,21 @@ com 88fc37a3c0a4dda553bdcfc80c178a58247f42fb...12fc37a3c0a4dda553bdcfc80c178a582
 com 88fc37a3c0a4dda553bdcfc80c178a58247f42fb mit
 <span class="emoji" aria-label="thumbs up">👍</span>
 <a href="mailto:mail@domain.com" class="mailto">mail@domain.com</a>
-<a href="http://localhost:3000/mention-user" class="mention">@mention-user</a> test
-<a href="http://localhost:3000/user13/repo11/issues/123" class="ref-issue">#123</a>
+<a href="/mention-user" class="mention">@mention-user</a> test
+<a href="/user13/repo11/issues/123" class="ref-issue">#123</a>
   space`
 
 	assert.EqualValues(t, expected, RenderCommitBody(context.Background(), testInput, testMetas))
 }
 
 func TestRenderCommitMessage(t *testing.T) {
-	expected := `space <a href="http://localhost:3000/mention-user" class="mention">@mention-user</a>  `
+	expected := `space <a href="/mention-user" class="mention">@mention-user</a>  `
 
 	assert.EqualValues(t, expected, RenderCommitMessage(context.Background(), testInput, testMetas))
 }
 
 func TestRenderCommitMessageLinkSubject(t *testing.T) {
-	expected := `<a href="https://example.com/link" class="default-link muted">space </a><a href="http://localhost:3000/mention-user" class="mention">@mention-user</a>`
+	expected := `<a href="https://example.com/link" class="default-link muted">space </a><a href="/mention-user" class="mention">@mention-user</a>`
 
 	assert.EqualValues(t, expected, RenderCommitMessageLinkSubject(context.Background(), testInput, "https://example.com/link", testMetas))
 }
@@ -155,14 +155,14 @@ com 88fc37a3c0a4dda553bdcfc80c178a58247f42fb mit
 <span class="emoji" aria-label="thumbs up">👍</span>
 mail@domain.com
 @mention-user test
-<a href="http://localhost:3000/user13/repo11/issues/123" class="ref-issue">#123</a>
+<a href="/user13/repo11/issues/123" class="ref-issue">#123</a>
   space  
 `
 	assert.EqualValues(t, expected, RenderIssueTitle(context.Background(), testInput, testMetas))
 }
 
 func TestRenderMarkdownToHtml(t *testing.T) {
-	expected := `<p>space <a href="http://localhost:3000/mention-user" rel="nofollow">@mention-user</a><br/>
+	expected := `<p>space <a href="/mention-user" rel="nofollow">@mention-user</a><br/>
 /just/a/path.bin
 <a href="https://example.com/file.bin" rel="nofollow">https://example.com/file.bin</a>
 <a href="/file.bin" rel="nofollow">local link</a>
@@ -179,7 +179,7 @@ com 88fc37a3c0a4dda553bdcfc80c178a58247f42fb...12fc37a3c0a4dda553bdcfc80c178a582
 com 88fc37a3c0a4dda553bdcfc80c178a58247f42fb mit
 <span class="emoji" aria-label="thumbs up">👍</span>
 <a href="mailto:mail@domain.com" rel="nofollow">mail@domain.com</a>
-<a href="http://localhost:3000/mention-user" rel="nofollow">@mention-user</a> test
+<a href="/mention-user" rel="nofollow">@mention-user</a> test
 #123
 space</p>
 `
diff --git a/routers/common/markup.go b/routers/common/markup.go
index 7819ee72276f..2d5638ef6123 100644
--- a/routers/common/markup.go
+++ b/routers/common/markup.go
@@ -34,7 +34,8 @@ func RenderMarkup(ctx *context.Base, repo *context.Repository, mode, text, urlPr
 		if err := markdown.RenderRaw(&markup.RenderContext{
 			Ctx: ctx,
 			Links: markup.Links{
-				Base: urlPrefix,
+				AbsolutePrefix: true,
+				Base:           urlPrefix,
 			},
 		}, strings.NewReader(text), ctx.Resp); err != nil {
 			ctx.Error(http.StatusInternalServerError, err.Error())
@@ -79,7 +80,8 @@ func RenderMarkup(ctx *context.Base, repo *context.Repository, mode, text, urlPr
 	if err := markup.Render(&markup.RenderContext{
 		Ctx: ctx,
 		Links: markup.Links{
-			Base: urlPrefix,
+			AbsolutePrefix: true,
+			Base:           urlPrefix,
 		},
 		Metas:        meta,
 		IsWiki:       wiki,
diff --git a/services/mailer/mail.go b/services/mailer/mail.go
index 38973ea9352f..a63ba7a52af0 100644
--- a/services/mailer/mail.go
+++ b/services/mailer/mail.go
@@ -222,7 +222,8 @@ func composeIssueCommentMessages(ctx *mailCommentContext, lang string, recipient
 	body, err := markdown.RenderString(&markup.RenderContext{
 		Ctx: ctx,
 		Links: markup.Links{
-			Base: ctx.Issue.Repo.HTMLURL(),
+			AbsolutePrefix: true,
+			Base:           ctx.Issue.Repo.HTMLURL(),
 		},
 		Metas: ctx.Issue.Repo.ComposeMetas(ctx),
 	}, ctx.Content)
diff --git a/services/mailer/mail_test.go b/services/mailer/mail_test.go
index e300aeccb0c1..d87c57ffe750 100644
--- a/services/mailer/mail_test.go
+++ b/services/mailer/mail_test.go
@@ -8,6 +8,8 @@ import (
 	"context"
 	"fmt"
 	"html/template"
+	"io"
+	"mime/quotedprintable"
 	"regexp"
 	"strings"
 	"testing"
@@ -19,6 +21,7 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/setting"
 
 	"github.com/stretchr/testify/assert"
@@ -67,6 +70,12 @@ func prepareMailerTest(t *testing.T) (doer *user_model.User, repo *repo_model.Re
 func TestComposeIssueCommentMessage(t *testing.T) {
 	doer, _, issue, comment := prepareMailerTest(t)
 
+	markup.Init(&markup.ProcessorHelper{
+		IsUsernameMentionable: func(ctx context.Context, username string) bool {
+			return username == doer.Name
+		},
+	})
+
 	setting.IncomingEmail.Enabled = true
 	defer func() { setting.IncomingEmail.Enabled = false }()
 
@@ -77,7 +86,8 @@ func TestComposeIssueCommentMessage(t *testing.T) {
 	msgs, err := composeIssueCommentMessages(&mailCommentContext{
 		Context: context.TODO(), // TODO: use a correct context
 		Issue:   issue, Doer: doer, ActionType: activities_model.ActionCommentIssue,
-		Content: "test body", Comment: comment,
+		Content: fmt.Sprintf("test @%s %s#%d body", doer.Name, issue.Repo.FullName(), issue.Index),
+		Comment: comment,
 	}, "en-US", recipients, false, "issue comment")
 	assert.NoError(t, err)
 	assert.Len(t, msgs, 2)
@@ -96,6 +106,20 @@ func TestComposeIssueCommentMessage(t *testing.T) {
 	assert.Equal(t, "<user2/repo1/issues/1/comment/2@localhost>", gomailMsg.GetHeader("Message-ID")[0], "Message-ID header doesn't match")
 	assert.Equal(t, "<mailto:"+replyTo+">", gomailMsg.GetHeader("List-Post")[0])
 	assert.Len(t, gomailMsg.GetHeader("List-Unsubscribe"), 2) // url + mailto
+
+	var buf bytes.Buffer
+	gomailMsg.WriteTo(&buf)
+
+	b, err := io.ReadAll(quotedprintable.NewReader(&buf))
+	assert.NoError(t, err)
+
+	// text/plain
+	assert.Contains(t, string(b), fmt.Sprintf(`( %s )`, doer.HTMLURL()))
+	assert.Contains(t, string(b), fmt.Sprintf(`( %s )`, issue.HTMLURL()))
+
+	// text/html
+	assert.Contains(t, string(b), fmt.Sprintf(`href="%s"`, doer.HTMLURL()))
+	assert.Contains(t, string(b), fmt.Sprintf(`href="%s"`, issue.HTMLURL()))
 }
 
 func TestComposeIssueMessage(t *testing.T) {