val headers : t ‑> Email_message.Email_headers.t
val last_header : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> Email_message.Email_headers.Name.t ‑> Email_message.Email_headers.Value.t option
val find_all_headers : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> Email_message.Email_headers.Name.t ‑> Email_message.Email_headers.Value.t list
val add_header : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> name:string ‑> value:string ‑> t
val add_headers : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> (string * string) list ‑> t
val set_header : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> name:string ‑> value:string ‑> t
val add_header_at_bottom : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> name:string ‑> value:string ‑> t
val add_headers_at_bottom : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> (string * string) list ‑> t
val set_headers : t ‑> Email_message.Email_headers.t ‑> t
val set_header_at_bottom : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> name:string ‑> value:string ‑> t
val smash_and_add_header : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> name:string ‑> value:string ‑> t
val modify_headers : t ‑> f:(Email_message.Email_headers.t ‑> Email_message.Email_headers.t) ‑> t
val filter_headers : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> f:(name:Email_message.Email_headers.Name.t ‑> value:Email_message.Email_headers.Value.t ‑> bool) ‑> t
val map_headers : ?whitespace:Email_message.Email_headers.Whitespace.t ‑> t ‑> f:(name:Email_message.Email_headers.Name.t ‑> value:Email_message.Email_headers.Value.t ‑> string) ‑> t