# Implementation quirks

This page documents unusual behavior of the maddy protocols implementations.
Some of these problems break standards, some don't but still can hurt
interoperability.

## SMTP

- `for` field is never included in the `Received` header field.

  This is allowed by [RFC 2821].

## IMAP

### `sql`

- `\Recent` flag is not reset in all cases.

  This _does not_ break [RFC 3501]. Clients relying on it will work (much) less
  efficiently.

[RFC 2821]: https://tools.ietf.org/html/rfc2821
[RFC 3501]: https://tools.ietf.org/html/rfc3501