deltachat/
smtp.rs

1//! # SMTP transport module.
2
3mod connect;
4pub mod send;
5
6use anyhow::{bail, format_err, Context as _, Error, Result};
7use async_smtp::response::{Category, Code, Detail};
8use async_smtp::{EmailAddress, SmtpTransport};
9use tokio::task;
10
11use crate::chat::{add_info_msg_with_cmd, ChatId};
12use crate::config::Config;
13use crate::contact::{Contact, ContactId};
14use crate::context::Context;
15use crate::events::EventType;
16use crate::log::{error, info, warn};
17use crate::login_param::prioritize_server_login_params;
18use crate::login_param::{ConfiguredLoginParam, ConfiguredServerLoginParam};
19use crate::message::Message;
20use crate::message::{self, MsgId};
21use crate::mimefactory::MimeFactory;
22use crate::net::proxy::ProxyConfig;
23use crate::net::session::SessionBufStream;
24use crate::scheduler::connectivity::ConnectivityStore;
25use crate::stock_str::unencrypted_email;
26use crate::tools::{self, time_elapsed};
27
28#[derive(Default)]
29pub(crate) struct Smtp {
30    /// SMTP connection.
31    transport: Option<SmtpTransport<Box<dyn SessionBufStream>>>,
32
33    /// Email address we are sending from.
34    from: Option<EmailAddress>,
35
36    /// Timestamp of last successful send/receive network interaction
37    /// (eg connect or send succeeded). On initialization and disconnect
38    /// it is set to None.
39    last_success: Option<tools::Time>,
40
41    pub(crate) connectivity: ConnectivityStore,
42
43    /// If sending the last message failed, contains the error message.
44    pub(crate) last_send_error: Option<String>,
45}
46
47impl Smtp {
48    /// Create a new Smtp instances.
49    pub fn new() -> Self {
50        Default::default()
51    }
52
53    /// Disconnect the SMTP transport and drop it entirely.
54    pub fn disconnect(&mut self) {
55        if let Some(mut transport) = self.transport.take() {
56            // Closing connection with a QUIT command may take some time, especially if it's a
57            // stale connection and an attempt to send the command times out. Send a command in a
58            // separate task to avoid waiting for reply or timeout.
59            task::spawn(async move { transport.quit().await });
60        }
61        self.last_success = None;
62    }
63
64    /// Return true if smtp was connected but is not known to
65    /// have been successfully used the last 60 seconds
66    pub fn has_maybe_stale_connection(&self) -> bool {
67        if let Some(last_success) = self.last_success {
68            time_elapsed(&last_success).as_secs() > 60
69        } else {
70            false
71        }
72    }
73
74    /// Check whether we are connected.
75    pub fn is_connected(&self) -> bool {
76        self.transport.is_some()
77    }
78
79    /// Connect using configured parameters.
80    pub async fn connect_configured(&mut self, context: &Context) -> Result<()> {
81        if self.has_maybe_stale_connection() {
82            info!(context, "Closing stale connection.");
83            self.disconnect();
84        }
85
86        if self.is_connected() {
87            return Ok(());
88        }
89
90        self.connectivity.set_connecting(context).await;
91        let lp = ConfiguredLoginParam::load(context)
92            .await?
93            .context("Not configured")?;
94        let proxy_config = ProxyConfig::load(context).await?;
95        self.connect(
96            context,
97            &lp.smtp,
98            &lp.smtp_password,
99            &proxy_config,
100            &lp.addr,
101            lp.strict_tls(proxy_config.is_some()),
102            lp.oauth2,
103        )
104        .await
105    }
106
107    /// Connect using the provided login params.
108    #[expect(clippy::too_many_arguments)]
109    pub async fn connect(
110        &mut self,
111        context: &Context,
112        login_params: &[ConfiguredServerLoginParam],
113        password: &str,
114        proxy_config: &Option<ProxyConfig>,
115        addr: &str,
116        strict_tls: bool,
117        oauth2: bool,
118    ) -> Result<()> {
119        if self.is_connected() {
120            warn!(context, "SMTP already connected.");
121            return Ok(());
122        }
123
124        let from = EmailAddress::new(addr.to_string())
125            .with_context(|| format!("Invalid address {addr:?}"))?;
126        self.from = Some(from);
127
128        let login_params =
129            prioritize_server_login_params(&context.sql, login_params, "smtp").await?;
130        let mut first_error = None;
131        for lp in login_params {
132            info!(context, "SMTP trying to connect to {}.", &lp.connection);
133            let transport = match connect::connect_and_auth(
134                context,
135                proxy_config,
136                strict_tls,
137                lp.connection.clone(),
138                oauth2,
139                addr,
140                &lp.user,
141                password,
142            )
143            .await
144            {
145                Ok(transport) => transport,
146                Err(err) => {
147                    warn!(context, "SMTP failed to connect and authenticate: {err:#}.");
148                    first_error.get_or_insert(err);
149                    continue;
150                }
151            };
152
153            self.transport = Some(transport);
154            self.last_success = Some(tools::Time::now());
155
156            context.emit_event(EventType::SmtpConnected(format!(
157                "SMTP-LOGIN as {} ok",
158                lp.user,
159            )));
160            return Ok(());
161        }
162
163        Err(first_error.unwrap_or_else(|| format_err!("No SMTP connection candidates provided")))
164    }
165}
166
167pub(crate) enum SendResult {
168    /// Message was sent successfully.
169    Success,
170
171    /// Permanent error, message sending has failed.
172    Failure(Error),
173
174    /// Temporary error, the message should be retried later.
175    Retry,
176}
177
178/// Tries to send a message.
179pub(crate) async fn smtp_send(
180    context: &Context,
181    recipients: &[async_smtp::EmailAddress],
182    message: &str,
183    smtp: &mut Smtp,
184    msg_id: Option<MsgId>,
185) -> SendResult {
186    if std::env::var(crate::DCC_MIME_DEBUG).is_ok() {
187        info!(context, "SMTP-sending out mime message:\n{message}");
188    }
189
190    smtp.connectivity.set_working(context).await;
191
192    if let Err(err) = smtp
193        .connect_configured(context)
194        .await
195        .context("Failed to open SMTP connection")
196    {
197        smtp.last_send_error = Some(format!("{err:#}"));
198        return SendResult::Retry;
199    }
200
201    let send_result = smtp.send(context, recipients, message.as_bytes()).await;
202    smtp.last_send_error = send_result.as_ref().err().map(|e| e.to_string());
203
204    let status = match send_result {
205        Err(crate::smtp::send::Error::SmtpSend(err)) => {
206            // Remote error, retry later.
207            info!(context, "SMTP failed to send: {:?}.", &err);
208
209            let res = match err {
210                async_smtp::error::Error::Permanent(ref response) => {
211                    // Workaround for incorrectly configured servers returning permanent errors
212                    // instead of temporary ones.
213                    let maybe_transient = match response.code {
214                        // Sometimes servers send a permanent error when actually it is a temporary error
215                        // For documentation see <https://tools.ietf.org/html/rfc3463>
216                        Code {
217                            category: Category::MailSystem,
218                            detail: Detail::Zero,
219                            ..
220                        } => {
221                            // Ignore status code 5.5.0, see <https://support.delta.chat/t/every-other-message-gets-stuck/877/2>
222                            // Maybe incorrectly configured Postfix milter with "reject" instead of "tempfail", which returns
223                            // "550 5.5.0 Service unavailable" instead of "451 4.7.1 Service unavailable - try again later".
224                            //
225                            // Other enhanced status codes, such as Postfix
226                            // "550 5.1.1 <foobar@example.org>: Recipient address rejected: User unknown in local recipient table"
227                            // are not ignored.
228                            response.first_word() == Some("5.5.0")
229                        }
230                        _ => false,
231                    };
232
233                    if maybe_transient {
234                        info!(context, "Permanent error that is likely to actually be transient, postponing retry for later.");
235                        SendResult::Retry
236                    } else {
237                        info!(context, "Permanent error, message sending failed.");
238                        // If we do not retry, add an info message to the chat.
239                        // Yandex error "554 5.7.1 [2] Message rejected under suspicion of SPAM; https://ya.cc/..."
240                        // should definitely go here, because user has to open the link to
241                        // resume message sending.
242                        SendResult::Failure(format_err!("Permanent SMTP error: {}", err))
243                    }
244                }
245                async_smtp::error::Error::Transient(ref response) => {
246                    // We got a transient 4xx response from SMTP server.
247                    // Give some time until the server-side error maybe goes away.
248                    //
249                    // One particular case is
250                    // `450 4.1.2 <alice@example.org>: Recipient address rejected: Domain not found`.
251                    // known to be returned by Postfix.
252                    //
253                    // [RFC 3463](https://tools.ietf.org/html/rfc3463#section-3.2)
254                    // says "This code is only useful for permanent failures."
255                    // in X.1.1, X.1.2 and X.1.3 descriptions.
256                    //
257                    // Previous Delta Chat core versions
258                    // from 1.51.0 to 1.151.1
259                    // were treating such errors as permanent.
260                    //
261                    // This was later reverted because such errors were observed
262                    // for existing domains and turned out to be actually transient,
263                    // likely caused by nameserver downtime.
264                    info!(
265                        context,
266                        "Transient error {response:?}, postponing retry for later."
267                    );
268                    SendResult::Retry
269                }
270                _ => {
271                    info!(
272                        context,
273                        "Message sending failed without error returned by the server, retry later."
274                    );
275                    SendResult::Retry
276                }
277            };
278
279            // this clears last_success info
280            info!(context, "Failed to send message over SMTP, disconnecting.");
281            smtp.disconnect();
282
283            res
284        }
285        Err(crate::smtp::send::Error::Envelope(err)) => {
286            // Local error, job is invalid, do not retry.
287            smtp.disconnect();
288            warn!(context, "SMTP job is invalid: {err:#}.");
289            SendResult::Failure(err)
290        }
291        Err(crate::smtp::send::Error::NoTransport) => {
292            // Should never happen.
293            // It does not even make sense to disconnect here.
294            error!(context, "SMTP job failed because SMTP has no transport.");
295            SendResult::Failure(format_err!("SMTP has not transport"))
296        }
297        Err(crate::smtp::send::Error::Other(err)) => {
298            // Local error, job is invalid, do not retry.
299            smtp.disconnect();
300            warn!(context, "Unable to load SMTP job: {err:#}.");
301            SendResult::Failure(err)
302        }
303        Ok(()) => SendResult::Success,
304    };
305
306    if let SendResult::Failure(err) = &status {
307        if let Some(msg_id) = msg_id {
308            // We couldn't send the message, so mark it as failed
309            match Message::load_from_db(context, msg_id).await {
310                Ok(mut msg) => {
311                    if let Err(err) =
312                        message::set_msg_failed(context, &mut msg, &err.to_string()).await
313                    {
314                        error!(context, "Failed to mark {msg_id} as failed: {err:#}.");
315                    }
316                }
317                Err(err) => {
318                    error!(
319                        context,
320                        "Failed to load {msg_id} to mark it as failed: {err:#}."
321                    );
322                }
323            }
324        }
325    }
326    status
327}
328
329/// Sends message identified by `smtp` table rowid over SMTP connection.
330///
331/// Removes row if the message should not be retried, otherwise increments retry count.
332pub(crate) async fn send_msg_to_smtp(
333    context: &Context,
334    smtp: &mut Smtp,
335    rowid: i64,
336) -> anyhow::Result<()> {
337    if let Err(err) = smtp
338        .connect_configured(context)
339        .await
340        .context("SMTP connection failure")
341    {
342        smtp.last_send_error = Some(format!("{err:#}"));
343        return Err(err);
344    }
345
346    // Increase retry count as soon as we have an SMTP connection. This ensures that the message is
347    // eventually removed from the queue by exceeding retry limit even in case of an error that
348    // keeps happening early in the message sending code, e.g. failure to read the message from the
349    // database.
350    context
351        .sql
352        .execute("UPDATE smtp SET retries=retries+1 WHERE id=?", (rowid,))
353        .await
354        .context("failed to update retries count")?;
355
356    let Some((body, recipients, msg_id, retries)) = context
357        .sql
358        .query_row_optional(
359            "SELECT mime, recipients, msg_id, retries FROM smtp WHERE id=?",
360            (rowid,),
361            |row| {
362                let mime: String = row.get(0)?;
363                let recipients: String = row.get(1)?;
364                let msg_id: MsgId = row.get(2)?;
365                let retries: i64 = row.get(3)?;
366                Ok((mime, recipients, msg_id, retries))
367            },
368        )
369        .await?
370    else {
371        return Ok(());
372    };
373    if retries > 6 {
374        if let Some(mut msg) = Message::load_from_db_optional(context, msg_id).await? {
375            message::set_msg_failed(context, &mut msg, "Number of retries exceeded the limit.")
376                .await?;
377        }
378        context
379            .sql
380            .execute("DELETE FROM smtp WHERE id=?", (rowid,))
381            .await
382            .context("Failed to remove message with exceeded retry limit from smtp table")?;
383        return Ok(());
384    }
385    info!(
386        context,
387        "Try number {retries} to send message {msg_id} (entry {rowid}) over SMTP."
388    );
389
390    let recipients_list = recipients
391        .split(' ')
392        .filter_map(
393            |addr| match async_smtp::EmailAddress::new(addr.to_string()) {
394                Ok(addr) => Some(addr),
395                Err(err) => {
396                    warn!(context, "Invalid recipient: {} {:?}.", addr, err);
397                    None
398                }
399            },
400        )
401        .collect::<Vec<_>>();
402
403    let status = smtp_send(context, &recipients_list, body.as_str(), smtp, Some(msg_id)).await;
404
405    match status {
406        SendResult::Retry => {}
407        SendResult::Success => {
408            context
409                .sql
410                .execute("DELETE FROM smtp WHERE id=?", (rowid,))
411                .await?;
412        }
413        SendResult::Failure(ref err) => {
414            if err.to_string().contains("Invalid unencrypted mail") {
415                let res = context
416                    .sql
417                    .query_row_optional(
418                        "SELECT chat_id, timestamp FROM msgs WHERE id=?;",
419                        (msg_id,),
420                        |row| Ok((row.get::<_, ChatId>(0)?, row.get::<_, i64>(1)?)),
421                    )
422                    .await?;
423
424                if let Some((chat_id, timestamp_sort)) = res {
425                    let addr = context.get_config(Config::ConfiguredAddr).await?;
426                    let text = unencrypted_email(
427                        context,
428                        addr.unwrap_or_default()
429                            .split('@')
430                            .nth(1)
431                            .unwrap_or_default(),
432                    )
433                    .await;
434                    add_info_msg_with_cmd(
435                        context,
436                        chat_id,
437                        &text,
438                        crate::mimeparser::SystemMessage::InvalidUnencryptedMail,
439                        timestamp_sort,
440                        None,
441                        None,
442                        None,
443                        None,
444                    )
445                    .await?;
446                };
447            }
448            context
449                .sql
450                .execute("DELETE FROM smtp WHERE id=?", (rowid,))
451                .await?;
452        }
453    };
454
455    match status {
456        SendResult::Retry => Err(format_err!("Retry")),
457        SendResult::Success => {
458            if !context
459                .sql
460                .exists("SELECT COUNT(*) FROM smtp WHERE msg_id=?", (msg_id,))
461                .await?
462            {
463                msg_id.set_delivered(context).await?;
464            }
465            Ok(())
466        }
467        SendResult::Failure(err) => Err(format_err!("{}", err)),
468    }
469}
470
471/// Attempts to send queued MDNs.
472async fn send_mdns(context: &Context, connection: &mut Smtp) -> Result<()> {
473    loop {
474        if !context.ratelimit.read().await.can_send() {
475            info!(context, "Ratelimiter does not allow sending MDNs now.");
476            return Ok(());
477        }
478
479        let more_mdns = send_mdn(context, connection).await?;
480        if !more_mdns {
481            // No more MDNs to send or one of them failed.
482            return Ok(());
483        }
484    }
485}
486
487/// Tries to send all messages currently in `smtp`, `smtp_status_updates` and `smtp_mdns` tables.
488pub(crate) async fn send_smtp_messages(context: &Context, connection: &mut Smtp) -> Result<()> {
489    let ratelimited = if context.ratelimit.read().await.can_send() {
490        // add status updates and sync messages to end of sending queue
491        context.flush_status_updates().await?;
492        false
493    } else {
494        true
495    };
496
497    let rowids = context
498        .sql
499        .query_map(
500            "SELECT id FROM smtp ORDER BY id ASC",
501            (),
502            |row| {
503                let rowid: i64 = row.get(0)?;
504                Ok(rowid)
505            },
506            |rowids| {
507                rowids
508                    .collect::<std::result::Result<Vec<_>, _>>()
509                    .map_err(Into::into)
510            },
511        )
512        .await?;
513
514    info!(context, "Selected rows from SMTP queue: {rowids:?}.");
515    for rowid in rowids {
516        send_msg_to_smtp(context, connection, rowid)
517            .await
518            .context("Failed to send message")?;
519    }
520
521    // although by slow sending, ratelimit may have been expired meanwhile,
522    // do not attempt to send MDNs if ratelimited happened before on status-updates/sync:
523    // instead, let the caller recall this function so that more important status-updates/sync are sent out.
524    if !ratelimited {
525        send_mdns(context, connection)
526            .await
527            .context("Failed to send MDNs")?;
528    }
529    Ok(())
530}
531
532/// Tries to send MDN for message identified by `rfc724_mdn` to `contact_id`.
533///
534/// Attempts to aggregate additional MDNs for `contact_id` into sent MDN.
535///
536/// On failure returns an error without removing any `smtp_mdns` entries, the caller is responsible
537/// for removing the corresponding entry to prevent endless loop in case the entry is invalid, e.g.
538/// points to non-existent message or contact.
539///
540/// Returns true on success, false on temporary error.
541async fn send_mdn_rfc724_mid(
542    context: &Context,
543    rfc724_mid: &str,
544    contact_id: ContactId,
545    smtp: &mut Smtp,
546) -> Result<bool> {
547    let contact = Contact::get_by_id(context, contact_id).await?;
548    if contact.is_blocked() {
549        return Err(format_err!("Contact is blocked"));
550    }
551
552    // Try to aggregate additional MDNs into this MDN.
553    let additional_rfc724_mids: Vec<String> = context
554        .sql
555        .query_map(
556            "SELECT rfc724_mid
557             FROM smtp_mdns
558             WHERE from_id=? AND rfc724_mid!=?",
559            (contact_id, &rfc724_mid),
560            |row| {
561                let rfc724_mid: String = row.get(0)?;
562                Ok(rfc724_mid)
563            },
564            |rows| rows.collect::<Result<Vec<_>, _>>().map_err(Into::into),
565        )
566        .await?
567        .into_iter()
568        .collect();
569
570    let mimefactory = MimeFactory::from_mdn(
571        context,
572        contact_id,
573        rfc724_mid.to_string(),
574        additional_rfc724_mids.clone(),
575    )
576    .await?;
577    let rendered_msg = mimefactory.render(context).await?;
578    let body = rendered_msg.message;
579
580    let addr = contact.get_addr();
581    let recipient = async_smtp::EmailAddress::new(addr.to_string())
582        .map_err(|err| format_err!("invalid recipient: {} {:?}", addr, err))?;
583    let recipients = vec![recipient];
584
585    match smtp_send(context, &recipients, &body, smtp, None).await {
586        SendResult::Success => {
587            info!(context, "Successfully sent MDN for {rfc724_mid}.");
588            context
589                .sql
590                .transaction(|transaction| {
591                    let mut stmt =
592                        transaction.prepare("DELETE FROM smtp_mdns WHERE rfc724_mid = ?")?;
593                    stmt.execute((rfc724_mid,))?;
594                    for additional_rfc724_mid in additional_rfc724_mids {
595                        stmt.execute((additional_rfc724_mid,))?;
596                    }
597                    Ok(())
598                })
599                .await?;
600            Ok(true)
601        }
602        SendResult::Retry => {
603            info!(
604                context,
605                "Temporary SMTP failure while sending an MDN for {rfc724_mid}."
606            );
607            Ok(false)
608        }
609        SendResult::Failure(err) => Err(err),
610    }
611}
612
613/// Tries to send a single MDN. Returns true if more MDNs should be sent.
614async fn send_mdn(context: &Context, smtp: &mut Smtp) -> Result<bool> {
615    if !context.should_send_mdns().await? {
616        context.sql.execute("DELETE FROM smtp_mdns", []).await?;
617        return Ok(false);
618    }
619    info!(context, "Sending MDNs.");
620
621    context
622        .sql
623        .execute("DELETE FROM smtp_mdns WHERE retries > 6", [])
624        .await?;
625    let Some(msg_row) = context
626        .sql
627        .query_row_optional(
628            "SELECT rfc724_mid, from_id FROM smtp_mdns ORDER BY retries LIMIT 1",
629            [],
630            |row| {
631                let rfc724_mid: String = row.get(0)?;
632                let from_id: ContactId = row.get(1)?;
633                Ok((rfc724_mid, from_id))
634            },
635        )
636        .await?
637    else {
638        return Ok(false);
639    };
640    let (rfc724_mid, contact_id) = msg_row;
641
642    context
643        .sql
644        .execute(
645            "UPDATE smtp_mdns SET retries=retries+1 WHERE rfc724_mid=?",
646            (rfc724_mid.clone(),),
647        )
648        .await
649        .context("Failed to update MDN retries count")?;
650
651    match send_mdn_rfc724_mid(context, &rfc724_mid, contact_id, smtp).await {
652        Err(err) => {
653            // If there is an error, for example there is no message corresponding to the msg_id in the
654            // database, do not try to send this MDN again.
655            warn!(
656                context,
657                "Error sending MDN for {rfc724_mid}, removing it: {err:#}."
658            );
659            context
660                .sql
661                .execute("DELETE FROM smtp_mdns WHERE rfc724_mid = ?", (rfc724_mid,))
662                .await?;
663            Err(err)
664        }
665        Ok(false) => {
666            bail!("Temporary error while sending an MDN");
667        }
668        Ok(true) => {
669            // Successfully sent MDN.
670            Ok(true)
671        }
672    }
673}
deltachat/smtp.rs

deltachat/
smtp.rs
