Sample sketches issue an error at 8266 ESP12

[Proset2003]

Hi there
I'm use Arduino IDE v 1.8.6 & E-mail library v 2.1(old ver). That configuration is working sometime. I'm work with IMAP read E-mail part of library.
Some days ago I'm updated the library to last version. Unfortunately after that all sketches (my and all sample sketches for IMAP) issues an error at execution time. The error concerning with lack of memory. I'm set memory option 3 as required at readme.
This is sample messages from COM terminal:
Mailbox status changed

Total Messages: 8
New message 8, has been addedd, reading message...

Mailbox listening stopped

C: Mailbox listening stopped

Get UID...

C: get UID

UID is 149

C: UID is 149

Error, out of memory

! E: out of memory

Finished reading Email

C: finished reading Email

So question is this version of library works wit IMAP in ESP8266 ONLY with external memory?

[mobizt]

You should see the latest library examples and follow it because the breaking changes of API since v3.0.0.

For small memory device as ESP8266, you should be aware of it requires 16k+ memory reserved for BearSSL engine to work with iMAP protocol that fragmentation does not support.

This left only 10k+ remaining heap for your other code.

You should consider to use ESP32 or RaspberryPi Pico W that has much memory.

[mobizt]

For all IMAP examples with ESP8266 test, it can run without the any issue in Wemos D1 mini and NodeMCU.

Then the answer to your question is no.

[Proset2003]

Thank you very much for your's replay.
I'm use board ESP12E (noname) mounted on my own PCB it has 4MB flash. At IDE I'm select NodeMCU(but try another no success)

I'm compile original sample sketch from samples folder
memory use:(may be help for us because I'm not so strong for memory use in ESP)
Executable segment sizes:
ICACHE : 16384 - flash instruction cache
IROM : 491712 - code in flash (default or ICACHE_FLASH_ATTR)
IRAM : 29181 / 49152 - code in IRAM (IRAM_ATTR, ISRs...)
DATA : 3144 ) - initialized variables (global, static) in RAM/HEAP
RODATA : 4076 ) / 81920 - constants (global, static) in RAM/HEAP
BSS : 31272 ) - zeroed variables (global, static) in RAM/HEAP
So error "Out of memory is here".
What can I do to fix this situation.

[mobizt]

You can choose "Generic ESP8266 Module" instead.

You can check the free heap anywhere in your code or using this helper class to track your free heap to check the memory leaks situation.
https://github.com/mobizt/ESP-Mail-Client/blob/master/src/HeapStat.h

The option to store the IMAP result temporary in IMAP session.

ESP-Mail-Client/examples/IMAP/Search_And_Read/Search_And_Read.ino

Lines 157 to 172 in bda5e84

	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 = 128;

In some critical case, you can disable those options (left only header to be stored) and store the result in flash or sd instead.

I don't know what happen in your case, but I test with Wemos D1 mini pro and it works fine with all example code without any option modification unless the WiFi and login credentials.

[Proset2003]

So I'm use board with 4Mb flash (vs 16MB on D1 pro)
I'm trying all options you recommend set to false and use Heapinfo - this is result:
Initial loop(no attempt to read email)

Heap Info

Current: 7920, Min: 7920, Max: 7920, Diff_1: 0, Diff_1: 0

After trying to read email
! E: out of memory

Finished reading Email

Heap Info

Current: 8032, Min: 7312, Max: 8032, Diff_1: 112, Diff_21: 112

what it mean?
So this value should be more than 16000 ?

By the way I'm trying to use ESP32 but unfortunately compiler stalled on compiling (any sketch from E-mail samples, sketches with other sample library compiled ok) So I'm has some problems with my IDE config. I'm updated all platforms(8266 ESP32) to last version but no luck.

But I'm trying to...

[mobizt]

After investigation, it is my false that I ever though that SSL fragmentation in IMAP is not support or not possible once testing many years ago since v3.x,x development.

The issue at that time may be related to the core sdk instead of SSL fragmentation issue as I understand.

Now you can set the SSL buffer size lower than the default IMAP setting value (16k) to gain more free memory.

You can use setSSLBufferSize (<rx_buffer_size>, <tx_buffer_size>) before imap.connect in the setup like the following.

imap.setSSLBufferSize(2048, 1024);

[Proset2003]

Thank you for help
All standart sample sketches works now on ESP-12E board.
So I'm should to adopt my original sketch now.

[mobizt]

You can update the library without setting this option.