import re
sample_str = "This is a random sentence. This one is also random sentence but it contains an email address ---@---.com"
lst = re.findall('(?<!\S)[A-Z](?:(?).)*[^\s@]+@[^\s@]+', sample_str)
print(lst)
aW1wb3J0IHJlCgpzYW1wbGVfc3RyID0gIlRoaXMgaXMgYSByYW5kb20gc2VudGVuY2UuIFRoaXMgb25lIGlzIGFsc28gcmFuZG9tIHNlbnRlbmNlIGJ1dCBpdCBjb250YWlucyBhbiBlbWFpbCBhZGRyZXNzIC0tLUAtLS0uY29tIgpsc3QgPSByZS5maW5kYWxsKCcoPzwhXFMpW0EtWl0oPzooPyFbIT8uXSg/IVxTKSkuKSpbXlxzQF0rQFteXHNAXSsnLCBzYW1wbGVfc3RyKSAKCnByaW50KGxzdCk=