Errors on mail parsing

[gmalakov]

I see the following errors trying to parse emails

Error: no encoding found for charset [ks_c_5601-1987].
Error: no encoding found for [ks_c_5601-1987].
Error: no encoding found for charset [ks_c_5601-1987].
Error: no encoding found for [ks_c_5601-1987].
Error: no encoding found for charset [ks_c_5601-1987].
Error: no encoding found for [ks_c_5601-1987].
Error: no encoding found for charset [ks_c_5601-1987].
Error: no encoding found for [ks_c_5601-1987].
Error: no encoding found for charset [ks_c_5601-1987].
Error: no encoding found for [ks_c_5601-1987].
Error: no encoding found for charset [ks_c_5601-1987].
Unable to decode header [subject: =?utf-8?B?0JfQsNC/0LjRgtCy0LDQvdC1INGC0LXRhNC70L7QvdC+0LK=?=]: FormatException: Invalid encoding before padding (at character 48)
0JfQsNC/0LjRgtCy0LDQvdC1INGC0LXRhNC70L7QvdC+0LK=

Also I have seen errors parsing UTF7 in email titles