diff --git a/models/user/email_address.go b/models/user/email_address.go
index e310858f9..e916249e3 100644
--- a/models/user/email_address.go
+++ b/models/user/email_address.go
@@ -16,6 +16,7 @@ import (
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
+	"code.gitea.io/gitea/modules/validation"
 
 	"xorm.io/builder"
 )
@@ -161,7 +162,17 @@ func ValidateEmail(email string) error {
 		return ErrEmailInvalid{email}
 	}
 
-	// TODO: add an email allow/block list
+	// if there is no allow list, then check email against block list
+	if len(setting.Service.EmailDomainAllowList) == 0 &&
+		validation.IsEmailDomainListed(setting.Service.EmailDomainBlockList, email) {
+		return ErrEmailInvalid{email}
+	}
+
+	// if there is an allow list, then check email against allow list
+	if len(setting.Service.EmailDomainAllowList) > 0 &&
+		!validation.IsEmailDomainListed(setting.Service.EmailDomainAllowList, email) {
+		return ErrEmailInvalid{email}
+	}
 
 	return nil
 }
diff --git a/modules/validation/helpers.go b/modules/validation/helpers.go
index 3381846b8..f6e00f388 100644
--- a/modules/validation/helpers.go
+++ b/modules/validation/helpers.go
@@ -10,6 +10,8 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/gobwas/glob"
 )
 
 var externalTrackerRegex = regexp.MustCompile(`({?)(?:user|repo|index)+?(}?)`)
@@ -48,6 +50,29 @@ func IsValidSiteURL(uri string) bool {
 	return false
 }
 
+// IsEmailDomainListed checks whether the domain of an email address
+// matches a list of domains
+func IsEmailDomainListed(globs []glob.Glob, email string) bool {
+	if len(globs) == 0 {
+		return false
+	}
+
+	n := strings.LastIndex(email, "@")
+	if n <= 0 {
+		return false
+	}
+
+	domain := strings.ToLower(email[n+1:])
+
+	for _, g := range globs {
+		if g.Match(domain) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // IsAPIURL checks if URL is current Gitea instance API URL
 func IsAPIURL(uri string) bool {
 	return strings.HasPrefix(strings.ToLower(uri), strings.ToLower(setting.AppURL+"api"))
diff --git a/services/forms/user_form.go b/services/forms/user_form.go
index 1f5abf94e..c0eb03f55 100644
--- a/services/forms/user_form.go
+++ b/services/forms/user_form.go
@@ -13,10 +13,10 @@ import (
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/validation"
 	"code.gitea.io/gitea/modules/web/middleware"
 
 	"gitea.com/go-chi/binding"
-	"github.com/gobwas/glob"
 )
 
 // InstallForm form for installation page
@@ -103,29 +103,6 @@ func (f *RegisterForm) Validate(req *http.Request, errs binding.Errors) binding.
 	return middleware.Validate(errs, ctx.Data, f, ctx.Locale)
 }
 
-// IsEmailDomainListed checks whether the domain of an email address
-// matches a list of domains
-func IsEmailDomainListed(globs []glob.Glob, email string) bool {
-	if len(globs) == 0 {
-		return false
-	}
-
-	n := strings.LastIndex(email, "@")
-	if n <= 0 {
-		return false
-	}
-
-	domain := strings.ToLower(email[n+1:])
-
-	for _, g := range globs {
-		if g.Match(domain) {
-			return true
-		}
-	}
-
-	return false
-}
-
 // IsEmailDomainAllowed validates that the email address
 // provided by the user matches what has been configured .
 // The email is marked as allowed if it matches any of the
@@ -133,10 +110,10 @@ func IsEmailDomainListed(globs []glob.Glob, email string) bool {
 // domains in the blocklist, if any such list is not empty.
 func (f *RegisterForm) IsEmailDomainAllowed() bool {
 	if len(setting.Service.EmailDomainAllowList) == 0 {
-		return !IsEmailDomainListed(setting.Service.EmailDomainBlockList, f.Email)
+		return !validation.IsEmailDomainListed(setting.Service.EmailDomainBlockList, f.Email)
 	}
 
-	return IsEmailDomainListed(setting.Service.EmailDomainAllowList, f.Email)
+	return validation.IsEmailDomainListed(setting.Service.EmailDomainAllowList, f.Email)
 }
 
 // MustChangePasswordForm form for updating your password after account creation