fix(user): make registration more resilient to email failures

- Add BeforeCreate hook to validate email syntax before user creation
- Make email verification sending non-fatal during account creation
- Log warning when email fails to send but allow registration to succeed
- Track failed email sends with metrics
- Configure HELO domain for mail server to improve SMTP handshakes

Author: pcfreak30

db/models/user.go

@@ -32,6 +32,19 @@ type User struct {
 	PasswordResets     []PasswordReset
 }
 
+func (u *User) BeforeCreate(tx *gorm.DB) error {
+	if u.Email != "" {
+		verify, err := getEmailVerifier().Verify(u.Email)
+		if err != nil {
+			return err
+		}
+		if !verify.Syntax.Valid {
+			return errors.New("email is invalid")
+		}
+	}
+	return nil
+}
+
 func (u *User) BeforeUpdate(tx *gorm.DB) error {
 	var email string
 	var changed bool

service/mailer.go

@@ -162,6 +162,14 @@ func NewMailerService(templateRegistry *mailer.TemplateRegistry) (core.Service,
 			options = append(options, mail.WithUsername(mailCfg.Username))
 			options = append(options, mail.WithPassword(mailCfg.Password))
 
+			if mailCfg.Host != "" {
+				domain := mailCfg.Host
+				if ctx.Config().Config().Core.Domain != "" {
+					domain = ctx.Config().Config().Core.Domain
+				}
+				options = append(options, mail.WithHELO(domain))
+			}
+
 			client, err := mail.NewClient(mailCfg.Host, options...)
 			if err != nil {
 				ctx.Logger().Error("Failed to create mail client",

service/user.go

@@ -13,8 +13,10 @@ import (
 	"go.lumeweb.com/portal/db/models"
 	"go.lumeweb.com/portal/event"
 	dbHelper "go.lumeweb.com/portal/service/internal/db"
+	"go.lumeweb.com/portal/service/internal/mailer"
 	"go.lumeweb.com/portal/service/internal/user"
 	userInternal "go.lumeweb.com/portal/service/internal/user"
+	"go.uber.org/zap"
 	"golang.org/x/crypto/bcrypt"
 	"gorm.io/gorm"
 	"gorm.io/gorm/clause"
@@ -273,7 +275,11 @@ func (u UserServiceDefault) CreateAccount(ctx context.Context, email string, pas
 				}
 			} else if verifyEmail {
 				if err := u.SendEmailVerification(ctx, _user.ID); err != nil {
-					return nil, err
+					u.Logger().Warn("Failed to send email verification during account creation, but account was created successfully",
+						zap.Uint("user_id", _user.ID),
+						zap.String("email", _user.Email),
+						zap.Error(err))
+					mailer.MailerFailed.WithLabelValues(mailer.LabelOpSend).Inc()
 				}
 			}