some error with error display (i don't know how to describe accurate) about mail-send HOT 2 CLOSED

error[E0599]: the method `as_dyn_error` exists for reference `&mail_send::Error`, but its trait bounds were not satisfied
   --> mail/src/error.rs:15:13
    |
15  |     #[error("failed to send mail")]
    |             ^^^^^^^^^^^^^^^^^^^^^ method cannot be called on `&mail_send::Error` due to unsatisfied trait bounds
    |
   ::: /path/to/.cargo/registry/src/github.com-1ecc6299db9ec823/mail-send-0.3.1/src/lib.rs:139:1
    |
139 | pub enum Error {
    | --------------
    | |
    | doesn't satisfy `mail_send::Error: AsDynError<'_>`
    | doesn't satisfy `mail_send::Error: std::error::Error`
    |
    = note: the following trait bounds were not satisfied:
            `mail_send::Error: std::error::Error`
            which is required by `mail_send::Error: AsDynError<'_>`
            `&mail_send::Error: std::error::Error`
            which is required by `&mail_send::Error: AsDynError<'_>`