ESP32 Fail to read IMAP

[fullmetalbitch]

Hello fellow developers,

I've been working on setting up an IMAP email client on my ESP32 using the ESP_Mail_Client.h library. However, I've encountered a specific issue that I'd like to discuss and hopefully get some guidance on.

The Problem: When attempting to connect to the IMAP server, the library encounters a timeout during the authentication process. The error message in the debug output indicates "response read timed out," leading to a connection closure.

Here's a snippet of the debug output:

Connecting to Wi-Fi...

Connected with IP: 192.168.1.207

#### Connecting to IMAP server...

> C: ESP Mail Client v3.3.7

> C: connecting to IMAP server

> C: Host > imap.ukr.net

> C: Port > 993

> C: Free internal heap before TLS 209772

> C: Starting socket

> C: SSL/TLS negotiation

> C: seeding the random number generator

> C: setting up the SSL/TLS structure

! W: Skipping SSL Verification. INSECURE!

> C: setting hostname for TLS session

> C: perform the SSL/TLS handshake

> C: verifying peer X.509 certificate

#### IMAP server connected
> C: IMAP server connected

#### Checking the capability...

> C: check the capability

#### Logging in...

> C: send IMAP command, AUTHENTICATE PLAIN

> C: cleaning SSL connection

! E: response read timed out

#### Error, connection closed

! E: connection closed

The code is

#include <Arduino.h>
#include <WiFi.h>

#include <ESP_Mail_Client.h>

#define WIFI_SSID "ssid"
#define WIFI_PASSWORD "password"

#define IMAP_HOST "imap.ukr.net"

#define IMAP_PORT esp_mail_imap_port_993

#define AUTHOR_EMAIL "mymail@ukr.net"
#define AUTHOR_PASSWORD "mypassword"

void imapCallback(IMAP_Status status);

void printMessageData();

IMAPSession imap;

// Max messages in the search result
int max_result = 3;

// Array to store the UID of messages in search result
int msg_uid[3];

void setup()
{

    Serial.begin(115200);

    Serial.println();

    WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

    Serial.print("Connecting to Wi-Fi");

    while (WiFi.status() != WL_CONNECTED)
    {
        Serial.print(".");
        delay(300);
    }
    Serial.println();
    Serial.print("Connected with IP: ");
    Serial.println(WiFi.localIP());
    Serial.println();

    MailClient.networkReconnect(true);

    imap.debug(1);

    imap.callback(imapCallback);

    Session_Config config;

    config.server.host_name = IMAP_HOST;
    config.server.port = IMAP_PORT;
    config.login.email = AUTHOR_EMAIL;
    config.login.password = AUTHOR_PASSWORD;

    IMAP_Data imap_data;

    imap_data.fetch.uid.clear();

    imap_data.search.unseen_msg = true;

    // Don't download all to filesystem
    imap_data.download.header = false;
    imap_data.download.text = false;
    imap_data.download.html = false;
    imap_data.download.attachment = false;
    imap_data.download.inlineImg = false;

    // Store html/text message body in IMAPSession object
    imap_data.enable.html = true;
    imap_data.enable.text = true;

    imap_data.enable.recent_sort = true;

    // Max messages in the search result
    imap_data.limit.search = max_result;

    imap_data.limit.msg_size = 2048;

    imap_data.limit.attachment_size = 1024 * 1024 * 5;

    if (!imap.connect(&config, &imap_data))
        return;

    if (!imap.selectFolder(F("INBOX")))
        return;

    // We search the unseen messages first to get its UID and stored in msg_uid.
    imap_data.search.criteria = F("SEARCH NEW"); // or "SEARCH RECENT"
    MailClient.readMail(&imap, false /* keep session open for fetching message in opened mailbox later */);

    // We already get the search result message, fetch it

    // Fetch the messages using UID stored in msg_uid one by one
    for (int i = 0; i < max_result; i++)
    {
        imap_data.search.criteria.clear();

        // Now Fech message by UID stored in msg_uid
        imap_data.fetch.uid = msg_uid[i];
        MailClient.readMail(&imap, false /* keep session open for fetching message in opened mailbox later */);
    }

    imap.closeSession();
    imap.empty();
}

void loop()
{
}

void imapCallback(IMAP_Status status)
{
    Serial.println(status.info());

    if (status.success())
    {
        // If this is the search result (imap contains only header info),
        // store the message UID that we can fetch for its body later.
        if (imap.headerOnly())
        {
            int matches_count = 0;
            for (size_t i = 0; i < imap.data().msgItems.size(); i++)
            {
                // You can compare the message subject with text you want from
                // imap.data().msgItems[i].subject before storing its UID in msg_uid

                msg_uid[i] = imap.data().msgItems[i].UID;
                matches_count++;
            }

            max_result = matches_count;
        }
        else
        {
            // This is the fetch result, print the whole message (header + body)
            printMessageData();
        }

        imap.empty();
    }
}

void printMessageData()
{

    IMAP_MSG_Item msg = imap.data().msgItems[0]; // msgItems contains only one message from fetch

    Serial.println("****************************");

    ESP_MAIL_PRINTF("Number: %d\n", msg.msgNo);
    ESP_MAIL_PRINTF("UID: %d\n", msg.UID);
    ESP_MAIL_PRINTF("Messsage-ID: %s\n", msg.ID);
    ESP_MAIL_PRINTF("Flags: %s\n", msg.flags);

    ESP_MAIL_PRINTF("Attachment: %s\n", msg.hasAttachment ? "yes" : "no");

    if (strlen(msg.acceptLang))
        ESP_MAIL_PRINTF("Accept Language: %s\n", msg.acceptLang);
    if (strlen(msg.contentLang))
        ESP_MAIL_PRINTF("Content Language: %s\n", msg.contentLang);
    if (strlen(msg.from))
        ESP_MAIL_PRINTF("From: %s\n", msg.from);
    if (strlen(msg.sender))
        ESP_MAIL_PRINTF("Sender: %s\n", msg.sender);
    if (strlen(msg.to))
        ESP_MAIL_PRINTF("To: %s\n", msg.to);
    if (strlen(msg.cc))
        ESP_MAIL_PRINTF("CC: %s\n", msg.cc);
    if (strlen(msg.date))
    {
        ESP_MAIL_PRINTF("Date: %s\n", msg.date);
        ESP_MAIL_PRINTF("Timestamp: %d\n", (int)MailClient.Time.getTimestamp(msg.date));
    }
    if (strlen(msg.subject))
        ESP_MAIL_PRINTF("Subject: %s\n", msg.subject);
    if (strlen(msg.reply_to))
        ESP_MAIL_PRINTF("Reply-To: %s\n", msg.reply_to);
    if (strlen(msg.return_path))
        ESP_MAIL_PRINTF("Return-Path: %s\n", msg.return_path);
    if (strlen(msg.in_reply_to))
        ESP_MAIL_PRINTF("In-Reply-To: %s\n", msg.in_reply_to);
    if (strlen(msg.references))
        ESP_MAIL_PRINTF("References: %s\n", msg.references);
    if (strlen(msg.comments))
        ESP_MAIL_PRINTF("Comments: %s\n", msg.comments);
    if (strlen(msg.keywords))
        ESP_MAIL_PRINTF("Keywords: %s\n", msg.keywords);

    if (strlen(msg.text.content))
        ESP_MAIL_PRINTF("Text Message: %s\n", msg.text.content);
    if (strlen(msg.text.charSet))
        ESP_MAIL_PRINTF("Text Message Charset: %s\n", msg.text.charSet);
    if (strlen(msg.text.transfer_encoding))
        ESP_MAIL_PRINTF("Text Message Transfer Encoding: %s\n", msg.text.transfer_encoding);
    if (strlen(msg.html.content))
        ESP_MAIL_PRINTF("HTML Message: %s\n", msg.html.content);
    if (strlen(msg.html.charSet))
        ESP_MAIL_PRINTF("HTML Message Charset: %s\n", msg.html.charSet);
    if (strlen(msg.html.transfer_encoding))
        ESP_MAIL_PRINTF("HTML Message Transfer Encoding: %s\n\n", msg.html.transfer_encoding);

    Serial.println();
}

Required settings:

Incoming Mail Server (IMAP): imap.ukr.net.
Port: 993.
Connection: SSL encrypted.
Secure Password Authentication (SPA) is disabled.

Comparative Library: Interestingly, I also tried the ESP32_MailClient.h library, which does work. However, it's not without its issues. While it successfully connects, it sometimes causes my ESP32 to restart unexpectedly.

Possible Causes and Solutions: I've considered that this issue might stem from network connectivity, IMAP server configuration, or compatibility with the ESP_Mail_Client.h library. I've ensured my Wi-Fi credentials are correct and verified the IMAP server settings. The decision to skip SSL verification is marked as "INSECURE," which could contribute to the problem. Additionally, library updates could potentially address this issue.

Request for Assistance: Has anyone else encountered a similar timeout issue with the ESP_Mail_Client.h library during authentication? Any insights into what might be causing this and how to resolve it would be greatly appreciated. Furthermore, if you have any suggestions for stabilizing the ESP32_MailClient.h library to prevent restarts, I'd love to hear them.

Thank you in advance for your help!

[mobizt]

The access denied with unrecognized reply.

Please set debug level to 4096 and post the result again.

[mobizt]

You should say another old library because the two libraries are totally difference.

[mobizt]

Please uninstall v3.3.7 and install v3.4.0 using zip file.

[fullmetalbitch]

Still not working, but don't rush, I can wait :)

> C: ESP Mail Client v3.4.0
#### Error, NTP server time reading timed out
! E: NTP server time reading timed out
> C: connecting to IMAP server
> C: Host > imap.ukr.net
> C: Port > 993
* OK IMAP4 ready


#### IMAP server connected
> C: IMAP server connected

#### Checking the capability...
> C: check the capability
xmail CAPABILITY
* CAPABILITY IMAP4rev1 IDLE ID XLIST NAMESPACE AUTH=PLAIN
xmail OK completed

#### Logging in...
> C: send IMAP command, AUTHENTICATE PLAIN
xmail AUTHENTICATE PLAIN
+ 

That's it, I've been waiting for over 5 minutes. I think this is not the most critical fix, so don't get distracted from the main work.

[mobizt]

Now issue was fixed already in v3.4.0.

[fullmetalbitch]

It's alive!!! I love you!!!