try:
	with open(sys.argv[1],"r" ) as csvfile:
		emails = csv.reader(csvfile, delimiter=b';')
		for row in emails:
			pn_tuple.append(row)
except IOError as e:
	print(e.errno, e.strerror)
	print("Cannot open file",sys.argv[1])

root = ET.Element("log")
root.set("action","add")
pn = len(pn_tuple)
for i in range(len(pn_tuple)):	
	xtag_mailbox = ET.SubElement(root,"mailbox")
	xtag_login = ET.SubElement(xtag_mailbox,"login")
	xtag_login.text = pn_tuple[i][0]
	xtag_fname = ET.SubElement(xtag_mailbox, "firstname")
	xtag_fname.text = pn_tuple[i][3]

tree = ET.ElementTree(root)
with open("file.xml", "w+", encoding='utf-8') as file:
	tree.write(file, xml_declaration=True, encoding='utf-8')

Traceback (most recent call last):
  File "./mail.py", line 133, in <module>
    tree.write(file, xml_declaration=True, encoding='utf8')
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 820, in write
    serialize(write, self._root, encoding, qnames, namespaces)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 939, in _serialize_xml
    _serialize_xml(write, e, encoding, qnames, None)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 939, in _serialize_xml
    _serialize_xml(write, e, encoding, qnames, None)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 937, in _serialize_xml
    write(_escape_cdata(text, encoding))
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 1073, in _escape_cdata
    return text.encode(encoding, "xmlcharrefreplace")
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc4 in position 4: ordinal not in range(128)

'Lenka', 'Do\xc4\x8dkalov\xc3\xa1'

with open(sys.argv[1],"r" ) as csvfile:

import codecs
with codecs.open(sys.argv[1],"r",'utf-8') as csvfile:

with open(sys.argv[1],"r",'utf-8') as csvfile:

with open(sys.argv[1], "r", encoding='utf-8') as csvfile: