# `MailglassInbound.MIMEError`
[🔗](https://github.com/szTheory/mailglass/blob/v2.3.0/lib/mailglass_inbound/mime_error.ex#L1)

Structured error for raw RFC 5322 MIME parse failures (`MailglassInbound.MIME`).

Mirrors the shape of `Mailglass.ConfigError` — a closed `:type` atom set, a
`[:type, :message, :cause, :context]` `defexception`, and a `Jason.Encoder`
derivation that **excludes `:cause`** so raw payload fragments never leak into
serialized output (logs, telemetry, admin). Match on the struct and `:type`,
never on the message string.

This struct is **package-local**: it does NOT implement the core
`Mailglass.Error` behaviour and does NOT join `Mailglass.Error`'s `@type`
union (that behaviour and union live in `mailglass` core). It is a plain
`defexception` with a `__types__/0` contract helper.

## Types

- `:inbound_mime_invalid` — the raw MIME source could not be parsed into a
  canonical internal representation. `:cause` carries the tagged gateway
  failure (`{:error, _}` / `{:throw, _}` / `{:exit, _}`); `:context` carries
  non-PII metadata such as `%{byte_size: n}`.
- `:gen_smtp_unavailable` — the optional `gen_smtp` dependency is not loaded,
  so MIME parsing is unavailable (degraded fallback).

See `docs/api_stability.md` for the locked `:type` atom set. Adding a value
requires a CHANGELOG entry + `@since` annotation (minor version bump);
removing a value requires a major version bump.

# `t`
*since 0.2.0* 

```elixir
@type t() :: %MailglassInbound.MIMEError{
  __exception__: true,
  cause: term() | nil,
  context: map(),
  message: String.t(),
  type: :inbound_mime_invalid | :gen_smtp_unavailable
}
```

# `__types__`
*since 0.2.0* 

Returns the closed set of valid `:type` atoms. Tested against `docs/api_stability.md`.

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*Consult [api-reference.md](api-reference.md) for complete listing*