win32.client com_error数组越界：Outlook批量下载附件失败求助

之前正常运行的Python函数，现在处理Outlook指定文件夹内的邮件时出现故障：处理约5000封邮件时一切正常，但处理到6500封邮件时，有近1000个附件无法下载，错误集中在attachment = message.Attachments.Item(1)这一行，抛出的异常信息如下：

com_error: (-2147352567, 'Exception occurred.', (4096, 'Microsoft Outlook', 'Array index out of bounds.', None, 0, -2147352567), None)

原函数完整代码：

def outlook_attachments() -> None:
    files_list = glob.glob('sort_test/*.txt')
    files_list = [x[11:] for x in files_list]
    # Connect to outlook.
    outlook = win32com.client.Dispatch("Outlook.Application").GetNamespace("MAPI")
    # Navigate to the Oasis folder.
    oasis_folder = outlook.GetDefaultFolder(4).folders("Oasis")
    # Define items inside Oasis folder.
    messages = oasis_folder.Items
    # Start reading messages in Oasis folder, start from 0.
    message = messages.GetFirst()
    # Defining path to save attachment to.
    path = 'fxg-notebooks/sort_test/'
    # Iterating through all Oasis messages, saving files that have not yet been saved.
    new_file_count = 0
    message_count = 0

    while True:
        # print('Messages processed: ', message_count, end='\r')
        message_count += 1
        # Read attachment from outlook message.
        try:
            attachment = message.Attachments.Item(1) <--- EXCEPTION OCCURS HERE
        # If GetNext() returned None, all messages have been read, break loop.
        except AttributeError:
            break
        # Check for attachment membership in files_list.
        try:
            if files_list.index(str(attachment)) >= 0:
                message = messages.GetNext()
                continue
        # If no membership, save attachment.
        except ValueError:
            attachment.SaveASFile(path + str(attachment))
            message = messages.GetNext()
            new_file_count += 1

    return None

• 问题根源：

  1. 直接调用Attachments.Item(1)默认假设所有邮件都至少有1个附件，但实际存在无附件的邮件，导致数组索引越界
  2. 用list.index()检查文件是否已存在，时间复杂度为O(n)，处理大量文件时效率极低
  3. 依赖GetFirst()/GetNext()的循环逻辑存在隐患，若遍历过程中Outlook文件夹内容变化，可能导致迭代异常或遗漏邮件

• 修复后的代码：

import glob
import win32com.client

def outlook_attachments() -> None:
    # 转成集合提升存在性检查效率
    existing_files = set()
    for file_path in glob.glob('sort_test/*.txt'):
        # 提取文件名，避免硬编码索引11，改用split更可靠
        file_name = file_path.split('/')[-1]
        existing_files.add(file_name)

    # 连接Outlook
    outlook = win32com.client.Dispatch("Outlook.Application").GetNamespace("MAPI")
    # 定位目标文件夹（4对应olFolderOutbox，若需收件箱可改为6）
    oasis_folder = outlook.GetDefaultFolder(4).Folders("Oasis")
    messages = oasis_folder.Items
    save_path = 'fxg-notebooks/sort_test/'
    new_file_count = 0
    message_count = 0

    # 改用for循环遍历，更稳定
    for message in messages:
        message_count += 1
        # 先检查是否有附件
        if message.Attachments.Count == 0:
            continue
        
        # 取第一个附件（如需保存所有附件可改为遍历message.Attachments）
        attachment = message.Attachments.Item(1)
        attachment_name = str(attachment)
        
        # 检查文件是否已存在
        if attachment_name in existing_files:
            continue
        
        # 保存附件，增加异常捕获避免单个失败中断全局
        try:
            attachment.SaveAsFile(f"{save_path}{attachment_name}")
            new_file_count += 1
            existing_files.add(attachment_name)  # 加入集合避免重复检查
        except Exception as e:
            print(f"保存附件 {attachment_name} 失败: {str(e)}")

    print(f"处理完成，共处理邮件 {message_count} 封，新增保存附件 {new_file_count} 个")

if __name__ == "__main__":
    outlook_attachments()

• 关键优化点：
  1. 将files_list转为集合existing_files，把文件存在性检查从O(n)优化到O(1)
  2. 增加message.Attachments.Count == 0的判断，跳过无附件的邮件，避免索引越界
  3. 改用for循环直接遍历messages，替代GetFirst()/GetNext()的不稳定逻辑
  4. 提取文件名时用split('/')[-1]替代硬编码索引11，适配不同路径格式
  5. 为附件保存操作单独增加异常捕获，单个附件保存失败不会中断整个批量任务
  6. 保存成功后将文件名加入集合，避免后续重复检查

内容的提问来源于stack exchange，提问作者rangeseeker