# -*- coding: utf-8 -*-
from __future__ import print_function
import re, sys, os, io
myFile="e://search.txt"
def searchStr(myFile):
    global findmail
    with io.open(myFile, encoding='utf-8') as f:
        head=[next(f) for x in range(5)]
        for i in head:
            res=re.findall('From:.*<*>', i)
            mail=''.join(res)
            findmail=mail[7:-1]
            return findmail
j=0
j=searchStr(myFile)
print(j)
print(findmail)

 from __future__ import print_function
import re, sys, os, io
myFile="e://search.txt"
def searchStr(myFile):
    with io.open(myFile, encoding='utf-8') as f:
        head=[next(f) for x in range(5)]
        for i in head:
            res=re.search('From:.*<*>', i)
            if not res:
                continue
            res.span()
            mail=i[res.start():res.end()]
        return mail
searchStr(myFile)
j=searchStr(myFile)
print(j[7:-1])

 >>> s='''dgfhgfhgfh gfhgfh gfhgfhfg 
hgfh ghfgh From: <ivanov@domain.ru>
gfdfgfd
fgdfgdf
fgdfgdffg for: <it@domain.ru>
gtdfgdf
fgdfgdfg
fgdfgdfg
fgdfgdfgd
'''
>>> lst = re.findall('From:.*<*>',s)
>>> for i in lst:
	print(i.split('<')[-1][:-1])
	
ivanov@domain.ru
>>>