If line == '@1' it's not in your list
if line == '$%' it's not in your list
if line == 'This is my %^$ line' it's not in your list
if line == '@' it is in your list
strings = ("!","@","#","$","%","^","&","*","(",")","_","+","=","-",".",",",")
with open("strings.txt") as f:
for line in f:
if any(i in line for i in strings):
print(line.strip('\n') + " was invalid.")
else:
print(line.strip('\n') + " was ok.")
f.close()

If you're using a with block like that, you don't need to close the file manually. any() is kind of advanced for where it seems you are, you could also iterate over the contents of the line, like so (normally I don't post answers to questions, but since you already have a working solution, I'll offer some tips):
# ...open file, define invalid chars, etc
for line in input:
valid = True
for char in line:
if char in invalid_characters:
valid = False
# or...
valid = valid and char not in invalid_characters
if valid:
print("{0} was ok".format(line))
else:
print("{0} was invalid".format(line))
# or...
print("{0} was {1}".format(line, "ok" if valid else "invalid"))