When using QQ email as a relay server in China, the issue of delayed message reception for Deltachat occurred

9h3884s2gz · August 8, 2026, 3:45am

Since May this year, when using Deltachat as the default relay to send messages, it has been restricted. Even if other relays are used instead, the delay or information loss is very serious.

After testing, using QQ email as a relay is reliable. None of the messages disappear, but the other party usually receives the messages five minutes later.

How to solve this problem? Is there anyone who can help modify Deltachat to shorten the time for sending polling to the QQ email server? Give us a Deltachat client that can be used as a relay based on QQ email in China.

Thank you very much.

I originally intended to deploy chatmail relays in China, but I saw on the forum that this method doesn’t work either, and the relays will also be intercepted. So, only QQ email can be used as the relay server for communication is the right method.

Steps to reproduce the problem

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Screen snapshots

Debug logs

Logs

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ian · August 8, 2026, 8:26am

Do these test cases also take 5 minutes?

If a QQ user sends another QQ user an email using webmail
If a foreign chatmail relay server & DC user sends a QQ DC user a message
If a QQ DC user sends a foreign chatmail relay server & DC user a message

We can’t do anything if the systems of QQ are lagging or if sending on QQ is lagging.

I would guess you are implying that QQ for reception is lacking IMAP idle and thus needs to be polled for messages. If I am interpreting this correctly, Delta Chat is already polling once every minute in such a case, not once every 5 minutes. So, if you are seeing a latency of 5 minutes, it might be coming from somewhere else.

github.com/chatmail/core

src/imap/idle.rs

main


      
          
                  // Fetch mail once we exit IDLE.
                  self.new_mail = true;
          
                  Ok(self)
              }
          }
          
          impl Imap {
              /// Idle using polling.
              pub(crate) async fn fake_idle(&mut self, context: &Context, watch_folder: &str) -> Result<()> {
                  let fake_idle_start_time = tools::Time::now();
          
                  info!(context, "IMAP-fake-IDLEing folder={:?}", watch_folder);
          
                  // Wait for 60 seconds or until we are interrupted.
                  match timeout(Duration::from_secs(60), self.idle_interrupt_receiver.recv()).await {
                      Err(_) => info!(context, "Fake IDLE finished."),
                      Ok(_) => info!(context, "Fake IDLE interrupted."),
                  }

9h3884s2gz · August 9, 2026, 4:22am

Thank you very much for your reply.

You guessed it right. I just think the interaction time interval between Deltachat and the QQ email server is too large.

I’ve tested it. Here’s the situation: When my mobile phone’s DC client uses a QQ email server for relay:

1.When others send emails to me via email, my Android DC client can receive the email information immediately.

2. When others use mobile DC clients (including both iPhone and Android systems) and configure QQ email server relay to send messages to my mobile DC client, it takes me 3 to 5 minutes to receive them.

3. Others use DC clients with chatmail relay configured to send messages to my mobile DC client, with a delay of 3 to 5 minutes, and sometimes even 24 hours.

9h3884s2gz · August 9, 2026, 4:30am

我再用中文回复一下，我的安卓手机装了Deltachat客户端，中继采用qq邮箱服务器。以下是接收情况：

1.其他人无论用任何邮箱给我发邮件，我网页邮箱和手机Deltachat都能马上收到邮件消息。

2.其他人也用手机Deltachat客户端时，他无论用QQ邮箱做中继还是用官方给出的chatmail做中继，他给我发Delta chat信息时，我的网页邮箱是能立刻收到信息邮件的，但我这边手机Deltachat上收到信息都是延迟5分钟甚至24小时的。

这个问题出在哪里？要怎么解决？谢谢了

9h3884s2gz · August 9, 2026, 4:47am

目前在中国有一个非常糟糕的现状是，我们无论用什么chatmail中继，都会被拦截，消息丢失和延迟都很严重。唯有用QQ邮箱服务器做中继是可行的不会被拦截，只要解决QQ邮箱服务器中继消息延迟的问题就可以了。

Currently in China, there is a very bad situation where no matter what chatmail relay we use, our messages will be blocked, and there are serious issues with message loss and delay. The only feasible solution is to use the QQ email server as the relay, which will not be blocked. All that needs to be addressed is the problem of message delay in the QQ email server relay.

Andreas · August 11, 2026, 7:19pm

Even non-public chatmail servers?

If you want I can give you 2 unlisted Chatmail servers: