osTicket-Version v1.18.1 (0375576)
Server-Software Apache/2.4.62 (Debian)
MySQL-Version 10.11.6
PHP-Version 8.3.14

I understand that PHP 8.3 is not officially supported yet, but I believe the issue is unrelated to the PHP version.

From time to time, I encounter the following error:

Excessive errors processing emails for ssl://mymailserver:995/POP (mymailservername <mymailaddress>).
Please manually check the Fetch Folder () [1/30 - 0/1]

Excessive errors processing emails

The osTicket log (in debug mode) shows:

Mail Fetcher
Invalid header value detected

I am aware that a quick solution is to manually delete the problematic email(s) from the mailbox. While this resolves the issue temporarily, it is frustrating to have to delete several emails manually each week.

Since I am using the latest osTicket version, all recommended patches mentioned in this forum have already been applied.

The issue is caused by spam emails. Below is an example of such an email:

Return-Path: return@return.postman.co.kr
Delivered-To: xxx
Received: from xxx (xxx [xxx])
by xxx (Postfix) with ESMTP id B329B1480F76
for <xxx>; Tue, 14 Jan 2025 05:17:34 +0100 (CET)
Authentication-Results: xxx;
dkim=pass (1024-bit key; unprotected) header.d=postman.co.kr header.i=@Postman.co.kr header.b="Y0lWkOYQ";
dkim-atps=neutral
Received: from send24.postman.co.kr (send24.postman.co.kr [119.207.76.24])
by xxx (Postfix) with SMTP id BC7D2A3338
for <xxx>; Tue, 14 Jan 2025 05:17:32 +0100 (CET)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1736828249;
s=sender; d=postman.co.kr;
h=From:To:Reply-to:Subject😃ate:List-Unsubscribe:Feedback-Id😛recedence:MIME-Version:Content-Type:Content-Transfer-Encoding;
bh=LfA/zocxzF+VgWGDHnRH+EgnFmZRRvFvLG1bjO/N76k=;
b=Y0lWkOYQZrBTstVi8QoIRkNQyrRqqcytoDb6rZaQfGTXd7ec7VYRMegSY/jkrqGV
rx/Vi8K/n2smjvtfMC2YayVRxI2qMiBy6SpmJbaJfQvPLzqHnWWoHi+fNxtIXO08zp7
+4kDlDpdrqwo0/yzAbs/hjHzR0YKde6Gd0LvVJQg=
From: "=?utf-8?B?U29waGll?=" <xxx>
To: "=?utf-8?B?Q1VTVA==?=" <xxx>
Reply-to: <xxx>
Subject: =?utf-8?B?UkVRVUVTVDpBRDgzNjFBUk1aLVJFRUw3?=
Date: Tue, 14 Jan 2025 13:17:29 +0900
X-WORKER_ID: <single.default_Worker_38>
X-MAIL_ID: <UE9TVF9JRD0yMDI1MDExNDAwMDAx>
X-MEMBER_ID: <TV9JRD1jYXRoeS5vbmVyaXZlcl8zNDQwNw==>
X-SEND_TYPE: <U1RZUEU9TUFTUw==>
X-LIST_TABLE: <TElTVF9UQUJMRT1FTVNfTUFTU19TRU5EX0xJU1Q=>
List-Unsubscribe: <mailto:unsubscribe@esp-send.humuson.com?subject=2025011400001^^cathy.oneriver_34407>, http://ums.pushpia.cn/ums/deny/unsubscription.jsp?p_id=2025011400001&m_id=cathy.oneriver_34407&chn=em
Feedback-Id: cathy.oneriver:2025011400001:cathy.oneriver_34407:ums
Precedence: bulk
X-Mailer: eMsSMTP Ver6.5( PLUTO-build 0322 )
MIME-Version: 1.0
Message-ID: 202501141317296349@send24.postman.co.kr
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: quoted-printable

<html>
<head>
<title></title>
</head>
<body><div style=3D"display:none"><img src=3D"http://ums.pushpia.cn/Check.html?TV9JRD1jYXRoeS5vbmVyaXZlcl8zNDQwNw=3D=3D&U1RZUEU9TUFTUw=3D=3D&TElTVF9UQUJMRT1FTVNfTUFTU19TRU5EX0xJU1Q=3D&UE9TVF9JRD0yMDI1MDExNDAwMDAx&VEM9MjAyNTAyMTM=3D&S0lORD1P" width=3D1 height=3D1></div>
Hello Dear,
Good day!
Hard Find Electronics is the distributor for electronic components and worked in the area more than 10years.
Our service:
1. 365days warranty
2. Hard to find parts
3. Short lead time(2days)
4. Free sample
5. Free shipping.
Our strong line:
IC: Microchip, TI, AD, LT, Xilinx, Maxim...
MLCC capacitors&resistors: Samsung, Murata, Yageo,TDK...
Diodes&Transistors: Vishay, ON, ST, TI, NXP...
Module&Connectors ,Relay: Traco, Hongfa, Omron, TE, Molex...
The below are our hot offer for your reference:
AD8361ARMZ-REEL7 AD 2023+ 8.67usd
AD8314ACPZ-RL7 AD 2021+ 1.28usd
LMH2110TM/NOPB AD 2022+ 4.72usd
PIC16F636-I/SL Microchip 2021+ 1.04usd
PIC12F510-I/SN Microchip 2021+ 0.38usd
PIC16F689-I/SS Microchip 2022+ 1.44usd
TPA3116D2DADR TI 2022+ 0.55usd
TPA3118D2DAPR TI 2022+ 0.63usd
TPA3251D2DDVR TI 2022+ 2.96usd
If you need any parts, Pls send inquires to me.
We will support you the best. 
 
Best regards=EF=BC=81 
Sophie  Sales Manager 
Hard Find Electronics 
315, Shahe Rod, Long Gang District, Shenzhen, CN, 518000 
Tel: +86-755-8418 8103            
Fax: +86-755-8418 8303
</body>
</html>

Does anyone have a suggestion for a permanent fix to this problem?