Lettre, Async blocks my code or is it not just responding fast?

help
1

I am using the lettre library and this is my rust code ..

#[derive(Debug, Clone)]
pub struct EmailService {
    mailer: AsyncSmtpTransport<Tokio1Executor>,
    from_email: String,
    from_name: String,
}

impl EmailService {
    pub fn init_service(config: &SmtpConfig) -> ServiceResult<Self> {
        let creds = Credentials::new(
            config.get_username().to_string(),
            config.get_password().to_string(),
        );
        let mailer = AsyncSmtpTransport::<Tokio1Executor>::starttls_relay(config.get_host())?
            .port(config.get_port())
            .credentials(creds)
            .build();
        Ok(Self {
            from_email: config.get_from_email().to_string(),
            from_name: config.get_from_name().to_string(),
            mailer,
        })
    }

    pub async fn send_email(&self, req: SendEmailRequest) -> ServiceResult<()> {
        let email = Message::builder()
            .from(format!("{0} <{1}>", self.from_name, self.from_email).parse()?)
            .to(req.to.parse()?)
            .subject(req.subject)
            .singlepart(
                SinglePart::builder()
                    .header(header::ContentType::TEXT_HTML)
                    .body(req.body),
            )?;
        let _result = self.mailer.send(email).await?;
        Ok(())
    }
}
}

I am using this service in Axum.. please help me.