diff --git a/models/user.go b/models/user.go
index 711bdc2953bb..9a15de0822cc 100644
--- a/models/user.go
+++ b/models/user.go
@@ -1072,18 +1072,46 @@ func validateUser(u *User) error {
 	return ValidateEmail(u.Email)
 }
 
-func updateUser(e Engine, u *User) error {
+func updateUser(e Engine, u *User, changePrimaryEmail bool) error {
 	if err := validateUser(u); err != nil {
 		return err
 	}
 
+	if changePrimaryEmail {
+		var emailAddress EmailAddress
+		has, err := e.Where("lower_email=?", strings.ToLower(u.Email)).Get(&emailAddress)
+		if err != nil {
+			return err
+		}
+		if !has {
+			// 1. Update old primary email
+			if _, err = e.Where("uid=? AND is_primary=?", u.ID, true).Cols("is_primary").Update(&EmailAddress{
+				IsPrimary: false,
+			}); err != nil {
+				return err
+			}
+
+			emailAddress.Email = u.Email
+			emailAddress.UID = u.ID
+			emailAddress.IsActivated = true
+			emailAddress.IsPrimary = true
+			if _, err := e.Insert(&emailAddress); err != nil {
+				return err
+			}
+		} else if _, err := e.ID(emailAddress).Cols("is_primary").Update(&EmailAddress{
+			IsPrimary: true,
+		}); err != nil {
+			return err
+		}
+	}
+
 	_, err := e.ID(u.ID).AllCols().Update(u)
 	return err
 }
 
 // UpdateUser updates user's information.
-func UpdateUser(u *User) error {
-	return updateUser(x, u)
+func UpdateUser(u *User, changePrimaryEmail bool) error {
+	return updateUser(x, u, changePrimaryEmail)
 }
 
 // UpdateUserCols update user according special columns
@@ -1112,7 +1140,7 @@ func UpdateUserSetting(u *User) (err error) {
 			return err
 		}
 	}
-	if err = updateUser(sess, u); err != nil {
+	if err = updateUser(sess, u, false); err != nil {
 		return err
 	}
 	return sess.Commit()
diff --git a/models/user_test.go b/models/user_test.go
index 34c465c58649..af1c1e5ee6a8 100644
--- a/models/user_test.go
+++ b/models/user_test.go
@@ -475,17 +475,17 @@ func TestUpdateUser(t *testing.T) {
 	user := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
 
 	user.KeepActivityPrivate = true
-	assert.NoError(t, UpdateUser(user))
+	assert.NoError(t, UpdateUser(user, false))
 	user = AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
 	assert.True(t, user.KeepActivityPrivate)
 
 	setting.Service.AllowedUserVisibilityModesSlice = []bool{true, false, false}
 	user.KeepActivityPrivate = false
 	user.Visibility = structs.VisibleTypePrivate
-	assert.Error(t, UpdateUser(user))
+	assert.Error(t, UpdateUser(user, false))
 	user = AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
 	assert.True(t, user.KeepActivityPrivate)
 
 	user.Email = "no mail@mail.org"
-	assert.Error(t, UpdateUser(user))
+	assert.Error(t, UpdateUser(user, true))
 }
diff --git a/routers/api/v1/admin/user.go b/routers/api/v1/admin/user.go
index 6bc9b849b1fc..67667f44d3b7 100644
--- a/routers/api/v1/admin/user.go
+++ b/routers/api/v1/admin/user.go
@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"strings"
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/context"
@@ -199,12 +200,20 @@ func EditUser(ctx *context.APIContext) {
 	if form.FullName != nil {
 		u.FullName = *form.FullName
 	}
+	var emailChanged bool
 	if form.Email != nil {
-		u.Email = *form.Email
-		if len(u.Email) == 0 {
+		email := strings.TrimSpace(*form.Email)
+		if len(email) == 0 {
 			ctx.Error(http.StatusUnprocessableEntity, "", fmt.Errorf("email is not allowed to be empty string"))
 			return
 		}
+		if err := models.ValidateEmail(email); err != nil {
+			ctx.InternalServerError(err)
+			return
+		}
+
+		emailChanged = !strings.EqualFold(u.Email, email)
+		u.Email = email
 	}
 	if form.Website != nil {
 		u.Website = *form.Website
@@ -243,7 +252,7 @@ func EditUser(ctx *context.APIContext) {
 		u.IsRestricted = *form.Restricted
 	}
 
-	if err := models.UpdateUser(u); err != nil {
+	if err := models.UpdateUser(u, emailChanged); err != nil {
 		if models.IsErrEmailAlreadyUsed(err) || models.IsErrEmailInvalid(err) {
 			ctx.Error(http.StatusUnprocessableEntity, "", err)
 		} else {
diff --git a/routers/api/v1/user/settings.go b/routers/api/v1/user/settings.go
index b4548e7443fa..b0f2a908efdf 100644
--- a/routers/api/v1/user/settings.go
+++ b/routers/api/v1/user/settings.go
@@ -74,7 +74,7 @@ func UpdateUserSettings(ctx *context.APIContext) {
 		ctx.User.KeepActivityPrivate = *form.HideActivity
 	}
 
-	if err := models.UpdateUser(ctx.User); err != nil {
+	if err := models.UpdateUser(ctx.User, false); err != nil {
 		ctx.InternalServerError(err)
 		return
 	}
diff --git a/routers/web/admin/users.go b/routers/web/admin/users.go
index acccc516bb45..31035c16ddd5 100644
--- a/routers/web/admin/users.go
+++ b/routers/web/admin/users.go
@@ -273,6 +273,11 @@ func EditUserPost(ctx *context.Context) {
 			ctx.RenderWithErr(errMsg, tplUserNew, &form)
 			return
 		}
+		if err := models.ValidateEmail(form.Email); err != nil {
+			ctx.Data["Err_Email"] = true
+			ctx.RenderWithErr(ctx.Tr("form.email_error"), tplUserNew, &form)
+			return
+		}
 		if u.Salt, err = models.GetUserSalt(); err != nil {
 			ctx.ServerError("UpdateUser", err)
 			return
@@ -307,7 +312,9 @@ func EditUserPost(ctx *context.Context) {
 
 	u.LoginName = form.LoginName
 	u.FullName = form.FullName
-	u.Email = form.Email
+	email := strings.TrimSpace(form.Email)
+	emailChanged := !strings.EqualFold(u.Email, email)
+	u.Email = email
 	u.Website = form.Website
 	u.Location = form.Location
 	u.MaxRepoCreation = form.MaxRepoCreation
@@ -327,7 +334,7 @@ func EditUserPost(ctx *context.Context) {
 		u.ProhibitLogin = form.ProhibitLogin
 	}
 
-	if err := models.UpdateUser(u); err != nil {
+	if err := models.UpdateUser(u, emailChanged); err != nil {
 		if models.IsErrEmailAlreadyUsed(err) {
 			ctx.Data["Err_Email"] = true
 			ctx.RenderWithErr(ctx.Tr("form.email_been_used"), tplUserEdit, &form)
diff --git a/routers/web/org/setting.go b/routers/web/org/setting.go
index e848939187ce..3414bb8dda93 100644
--- a/routers/web/org/setting.go
+++ b/routers/web/org/setting.go
@@ -96,7 +96,7 @@ func SettingsPost(ctx *context.Context) {
 	visibilityChanged := form.Visibility != org.Visibility
 	org.Visibility = form.Visibility
 
-	if err := models.UpdateUser(org); err != nil {
+	if err := models.UpdateUser(org, false); err != nil {
 		ctx.ServerError("UpdateUser", err)
 		return
 	}