是否有办法从PST文件中获取附件名称？

你可以先尝试用 ascii 进行解码。

print((msg.get_attachment(0).read_buffer(attach_size)).decode('ascii', errors="ignore"))
我认为微软使用了不止一种方式来对附件的不同部分进行编码，所以没有一种解码方式可以做到完美。如果ascii不能解码足够的内容，你可以把它们都试试。对于不同的Python版本，请查看here.
# 98 encodings in python3.5/6/7
decode = ['ascii','big5','big5hkscs','cp037','cp273',
          'cp424','cp437','cp500','cp720','cp737',
          'cp775','cp850','cp852','cp855','cp856',
          'cp857','cp858','cp860','cp861','cp862',
          'cp863','cp864','cp865','cp866','cp869',
          'cp874','cp875','cp932','cp949','cp950',
          'cp1006','cp1026','cp1125','cp1140','cp1250',
          'cp1251','cp1252','cp1253','cp1254','cp1255',
          'cp1256','cp1257','cp1258','cp65001','euc_jp',
          'euc_jis_2004','euc_jisx0213','euc_kr','gb2312','gbk',
          'gb18030','hz','iso2022_jp','iso2022_jp_1','iso2022_jp_2',
          'iso2022_jp_2004','iso2022_jp_3','iso2022_jp_ext','iso2022_kr','latin_1',
          'iso8859_2','iso8859_3','iso8859_4','iso8859_5','iso8859_6',
          'iso8859_7','iso8859_8','iso8859_9','iso8859_10','iso8859_11',
          'iso8859_13','iso8859_14','iso8859_15','iso8859_16','johab',
          'koi8_r','koi8_t','koi8_u','kz1048','mac_cyrillic',
          'mac_greek','mac_iceland','mac_latin2','mac_roman','mac_turkish',
          'ptcp154','shift_jis','shift_jis_2004','shift_jisx0213','utf_32',
          'utf_32_be','utf_32_le','utf_16','utf_16_be','utf_16_le',
          'utf_7','utf_8','utf_8_sig']
# Select the best decoder
items = []
for item in encode:
    attach_size = msg.get_attachment(0).get_size()
    content = (msg.get_attachment(0).read_buffer(attach_size)).decode(item, errors="ignore")
    # I know 'sample_content' is in the attachment, so it's easy to see which ones can decode it.
    if 'sample_content' in content:
        items.append(item)