Error when communicating with the mail server

[StefInP]

Steps to reproduce

1. Let the Cron job mail sync run or sync mailbox manually
2. With an admin profil, go to Configuration Parameters > Logging

Expected behavior

No errors during communicating with the mail server.

Actual behavior

I have a lot of :

• Horde_Imap_Client_Exception Error when communicating with the mail server Cron mail sync failed for account xx
  or
• ServiceException Could not fetch stats of mailbox xxx. IMAP error: Error when communicating with the mail server.
  or even
• ServiceException Could not fetch message source: Mail server denied authentication.

horde_imap.log
horde_imap 2 extract failed 22h14 anonymized.log

nextcloud.log
nextcloud 2 extrait.log

open_ssl test
open_ssl test result Mailo.txt

Mail app version

4.0.9

Nextcloud version

30.0.2 (AIO 10.0.0)

Mailserver or service

Mailo.com

Operating system

No response

PHP engine version

PHP 8.3

Nextcloud memory caching

No response

Web server

Apache (supported)

Database

PostgreSQL

Additional info

I'm not sure I should report this issue because I only have it with the Mailo.com mail server.
But I did a test with Thunderbird in debug mode overnight (sync every 10 minutes) => no error in Thunderbird logs.
So I think it's not necessarily due to the server but perhaps to the mail app.
That's why I've decided to bring the subject here.
@mat-m, you seems to bee a Mailo.com user, maybe you can give feedback ? Thanks.

I've tried to collect the log files above in the most targeted way possible (for a single occurrence of Cron mail sync error).
In the imap log, I have left it from the start of the cron job to the end.

Log files collected yesterday with NC30.0.2 / Mail 4.0.9.
Same issue today after update to NC30.0.4 / Mail 4.0.10
I have tried to increase the imap timeout without success.