diff --git a/internal/provider/providers/dnsomatic/provider.go b/internal/provider/providers/dnsomatic/provider.go
index 0032a3f5..d925d909 100644
--- a/internal/provider/providers/dnsomatic/provider.go
+++ b/internal/provider/providers/dnsomatic/provider.go
@@ -8,7 +8,6 @@ import (
 	"net/http"
 	"net/netip"
 	"net/url"
-	"regexp"
 	"strings"
 
 	"github.com/qdm12/ddns-updater/internal/models"
@@ -55,13 +54,10 @@ func New(data json.RawMessage, domain, host string,
 	return p, nil
 }
 
-var regexUsername = regexp.MustCompile(`^[a-zA-Z0-9+@._-]{3,25}$`)
-
 func (p *Provider) isValid() error {
 	switch {
-	case !regexUsername.MatchString(p.username):
-		return fmt.Errorf("%w: username %q does not match regex %q",
-			errors.ErrUsernameNotValid, p.username, regexUsername)
+	case p.username == "":
+		return fmt.Errorf("%w", errors.ErrUsernameNotSet)
 	case p.password == "":
 		return fmt.Errorf("%w", errors.ErrPasswordNotSet)
 	}
diff --git a/internal/provider/providers/dnsomatic/provider_test.go b/internal/provider/providers/dnsomatic/provider_test.go
index c19378a7..2088df0d 100644
--- a/internal/provider/providers/dnsomatic/provider_test.go
+++ b/internal/provider/providers/dnsomatic/provider_test.go
@@ -19,35 +19,8 @@ func Test_Provider_isValid(t *testing.T) {
 			provider: Provider{
 				password: "password",
 			},
-			errWrapped: errors.ErrUsernameNotValid,
-			errMessage: `username is not valid: username "" does not match regex "^[a-zA-Z0-9+@._-]{3,25}$"`,
-		},
-		"email_username": {
-			provider: Provider{
-				username: "a@a.ca",
-				password: "password",
-			},
-		},
-		"email_alias_username": {
-			provider: Provider{
-				username: "a+b@a.ca",
-				password: "password",
-			},
-		},
-		"dashes_username": {
-			provider: Provider{
-				username: "a-b-c",
-				password: "password",
-			},
-		},
-		"oversized_username": {
-			provider: Provider{
-				username: "aaaaaaaaaaaaaaaaaaaaaaaaaa",
-				password: "password",
-			},
-			errWrapped: errors.ErrUsernameNotValid,
-			errMessage: `username is not valid: username ` +
-				`"aaaaaaaaaaaaaaaaaaaaaaaaaa" does not match regex "^[a-zA-Z0-9+@._-]{3,25}$"`,
+			errWrapped: errors.ErrUsernameNotSet,
+			errMessage: `username is not set`,
 		},
 	}