notification services logs error when user has no email address

[wkloucek]

Describe the bug

The notification service logs an error when the user has no email address specified

Steps to reproduce

Steps to reproduce the behavior:

1. have the notification service up and running / configure to send emails
2. share something with a user that has no email address

Expected behavior

See no error log in the notifications service

Actual behavior

The notifications service logs {"level":"error","service":"notifications","error":"Mail Error: No recipient specified","event":"SendEmail","time":"2023-07-20T08:02:40.951025544Z","line":"github.com/owncloud/ocis/v2/services/notifications/pkg/service/service.go:124","message":"failed to send a message"}

This should be a "info" or better "debug" level log statement, because this is not an error.

Ideally we're checking first (before doing anything else) if:

• the user has an email address
• the user want's to receive emails

This prevents wasting CPU / Memory

The second point is already checked here and this could be extended for the email address!?:

ocis/services/notifications/pkg/service/service.go

Lines 210 to 222 in 531efe0

	func (s eventsNotifier) disableEmails(ctx context.Context, u *user.UserId) bool {
	granteeCtx := metadata.Set(ctx, middleware.AccountID, u.OpaqueId)
	if resp, err := s.valueService.GetValueByUniqueIdentifiers(granteeCtx,
	&settingssvc.GetValueByUniqueIdentifiersRequest{
	AccountUuid: u.OpaqueId,
	SettingId: defaults.SettingUUIDProfileDisableNotifications,
	},
	); err == nil {
	return resp.GetValue().GetValue().GetBoolValue()
	}
	return false
	}