/// Initializes the mail server: sets up the Telegram API client and
	/// validates all required configuration values.
	///
	/// # Arguments
	/// * `settings` - Parsed application configuration.
	///
	/// # Errors
	/// Returns an error if required configuration values are missing or invalid.
	/// Returns an error if required configuration values are missing or invalid,
	/// Telegram API client creation fails, or the address regex cannot be built.
	pub fn new (settings: config::Config) -> Result<MailServer> {
		let api_key = settings.get_string("api_key")
			.context("[smtp2tg.toml] missing \"api_key\" parameter.\n")?;
		let mut recipients = HashMap::new();
		for (name, value) in settings.get_table("recipients")
			.context("[smtp2tg.toml] missing table \"recipients\".\n")?
		{

		}
		let re_domains = domains.iter().map(|s| escape(s))
			.collect::<Vec<String>>().join("|");
		let address = RegexBuilder::new(&format!("^[a-z0-9][a-z0-9.-]*(@({re_domains}))?$"))
			.case_insensitive(true).build().stack()?;

		Ok(MailServer {
			data: vec!(),
			data: vec![],
			headers: None,
			tg,
			fields,
			address,
		})
	}

	pub fn get_id (&self, name: &str) -> Result<&ChatPeerId> {
		if self.address.is_match(name) {
			Ok(self.tg.get(name).unwrap_or(&self.tg.default))
		} else {
			bail!("Email address {name:?} is not from an allowed domain.");
	}	}

	/// Forwards the buffered email to each distinct destination chat, using the
	/// default chat for allowed addresses without a configured recipient.
	///
	/// Inlines the first plain-text body if the escaped message is below 4096
	/// bytes. Sends remaining text parts and decoded attachments as documents;
	/// HTML body parts are omitted. Leaves the buffered data and envelope intact.
	///
	/// Attempt to deliver one message
	/// # Errors
	/// Returns an error for a missing envelope, no recipients, a disallowed
	/// address, mail parsing or part extraction failures, or rejected closing
	/// `pre`/`code` tags in text passed to validation. Propagates media-group
	/// construction and Telegram request errors, including diagnostic sends.
	/// Delivery to earlier chats is not rolled back if a later send fails.
	async fn relay_mail (&self) -> Result<()> {
		if let Some(headers) = &self.headers {
			let mail = mail_parser::MessageParser::new().parse(&self.data)
				.context("Failed to parse mail.")?;

			// Adding all known addresses to recipient list, for anyone else adding default
			// Also if list is empty also adding default

				&& let Some(date) = mail.date()
			{
				reply.push(format!("<u><i>Date:</i></u> <code>{date}</code>"));
			}
			reply.push("</blockquote><pre>".into());
			let reply = reply.join("\n");

			let html_parts = mail.html_body_count();
			let text_parts = mail.text_body_count();
			let attachments = mail.attachment_count();
			let text_parts = mail.text_body().len();
			let html_parts = mail.html_body().len();
			if html_parts != text_parts {
				self.tg.debug(&format!("Hm, we have {html_parts} HTML parts and {text_parts} text parts.")).await?;
			}
			//let mut html_num = 0;
			let mut text_num = 0;
			let mut file_num = 0;
			// let's display first html or text part as body
			let mut body: String = "".into();
			// Display the first text part as the body if it fits.
			let mut body = String::new();
			/*
			 * actually I don't wanna parse that html stuff
			if html_parts > 0 {
			if text_parts > 0 {
				let text = mail.body_html(0).stack()?;
				if text.len() < 4096 - header_size {
					body = text;
					html_num = 1;
				}
			};
			*/
			if body.is_empty() && text_parts > 0 {
				let text = mail.body_text(0)
					.context("Failed to extract text from message")?
					.replace("\r\n", "\n");
				let text = validate(&text).stack()?;
				// 6:
				// - (headers)
				// - (mail text)
				// - 6: </pre>
				if text.len() < 4096 - ( reply.len() + 6 ) {
					body = text.to_string();
					body = text.into_owned();
					text_num = 1;
				}
			};
			let msg = format!("{}{}</pre>", reply, body);

			// and let's collect all other attachment parts
			let mut files_to_send = vec![];
			// Send remaining text-body parts followed by attachments.
			let files_to_send: Vec<_> = mail.text_body().skip(text_num)
			/*
			 * let's just skip html parts for now, they just duplicate text?
			while html_num < html_parts {
				files_to_send.push(mail.html_part(html_num).stack()?);
				html_num += 1;
			}
			*/
			while text_num < text_parts {
				files_to_send.push(mail.text_part(text_num.try_into().stack()?)
					.context("Failed to get text part from message.")?);
				text_num += 1;
			}
			while file_num < attachments {
				files_to_send.push(mail.attachment(file_num.try_into().stack()?)
				.chain(mail.attachments()).collect();
					.context("Failed to get file part from message.")?);
				file_num += 1;
			}

			for chat in rcpt {
				if !files_to_send.is_empty() {
					let mut files = vec![];
					// let mut first_one = true;
					for chunk in &files_to_send {
						let data: Vec<u8> = chunk.contents().to_vec();
						let data: Vec<u8> = chunk.decoded().to_vec();
						let mut filename: Option<String> = None;
						for header in chunk.headers() {
							if header.name() == "Content-Type" {
								match header.value() {
									mail_parser::HeaderValue::ContentType(contenttype) => {
										if let Some(fname) = contenttype.attribute("name") {
											filename = Some(fname.to_owned());
										}
									},
									_ => {
										self.tg.debug("Attachment has bad ContentType header.").await?;
									},
								};
							};
						for header in chunk.headers().iter()
							.filter(|header| header.raw_name().eq_ignore_ascii_case("Content-Type"))
						{
							match header.value() {
								mail_parser::HeaderValue::ContentType(contenttype) => {
									if let Some(fname) = contenttype.attribute("name") {
										filename = Some(fname.to_owned());
									}
								},
								_ => {
									self.tg.debug("Attachment has bad ContentType header.").await?;
								},
							};
						};
						};
						let filename = if let Some(fname) = filename {
							fname
						} else {
							"Attachment.txt".into()
						};
						files.push(Attachment {
							data: Cursor::new(data),
							name: filename,
							name: filename.unwrap_or_else(|| "Attachment.txt".into()),
						});
					}
					self.tg.sendgroup(chat, files, &msg).await?;
				} else {
					self.tg.send(chat, &msg).await?;
				}
			}