i now have three /8 blocks in my email filters.
25.0.0.0/8 in the UK, 53.0.0.0/8 in germany, and 133.0.0.0/8 in japan.
the “standard” email filters, built on “and/or” and “contains/does not contain”, break down when you’re dealing with 16.75 MILLION addresses.
they break down because you can’t just filter on 25. which appears in the middle and end of IP addresses, in message ID numbers, and, occaisionally, in the body of the message.
the result is A LOT of false positives: email which i can’t forward to the correct recipient, because it will get filtered AGAIN…
which is quite annoying. 😒
so, with the help of my friend robert, i built a regular expression to handle it:
\D25\.\d{1,3}\.\d{1,3}\.\d{1,3}\D
finds non-digit character followed by “25.”, followed by three repititions of one to three digits, interspersed by periods, followed by another non-digit character.
technically, this regex could be adapted to accomodate any IP address, which means that, theoretically, i have a whole new, easier, and faster method of processing spam. 😈
the next step is to learn how to search for a specific range of digits… 😈
ETA 191127 i discovered that you can’t specify a range of digits with a regex. for that, you need a script, which is too much work. also, i determined that i DON’T need the white space character at the beginning and end of the regular expression, because, sometimes, the IP address is surrounded by parentheses, square brackets, or both.
ETA 191128 i changed it from white space character — \s — to non-digit character — \D — because some IP addresses are surrounded by parentheses or square brackets, but some are surrounded by white space characters. the only thing \D doesn’t capture is an empty string, so the IP address can’t be the first thing in the line of text.
and, even with the \D, this regex, modified to capture 27.16.0.0/12 in china, captures 2.2019.11.27.23.41.02, which is part of the message ID on a LEGITIMATE message. 😖😒😠🤬
this is why i’m rerouting these messages, rather than summarily deleting them, which is my inclination… summarily deleting what i think is spam has come back to bite me in the ass often enough that i don’t do it any longer. 😒