Newbie Question

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David Jenkins
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Newbie Question

Mon Dec 20, 2021 10:24 am

Brand new to MailWasher, as of today. Looking forward to reduced aggravation due to ever-increasing volume of spam showing up in my inbox. Here's my first usage question:

I have lately been receiving much spam where the FROM address appears as gobbledygook@balderash, where gobbledegook and balderdash are non-sensical alpha strings. Example: sdWxtvCIucc@zXdftrFGGhw.

It takes extra effort to get addresses such as this placed on Outlook blacklist, and it doesn't really matter anyway, since the sender will just generate a different string when he sends the next message.

Is there a mechanism whereby MailWasher can be conditioned to reject all such mails? I'm guessing the clue would be that the domain does not include a suffix, but beyond that I don't know what could be used.

Appreciate the help - thanks!
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rusticdog
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Re: Newbie Question

Mon Dec 20, 2021 6:35 pm

So if they don't have a domain suffix they should be fairly easy to catch.

I use this Custom Filter to look at any email address that shouldn't be considered valid, which would be worth a try. Screenshot attached.

Settings >> Spam Tools >> Filters >> clcik Add Filter >> enter details below, copy/paste the regular expression text.
It's set to if the FROM, DOESN'T CONTAIN, REGEX

Code: Select all

[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,4}
filter.png
filter.png (40.1 KiB) Viewed 416 times
David Jenkins
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Re: Newbie Question

Tue Dec 21, 2021 3:50 am

Thanks for the input.

I am fairly competent regarding regexes (taught intro classes, etc.) but could not see an obvious way of applying them as part of MW processing. Now that I see how in the MW context, I'm going to be able to do all sorts of screening that was heretofore impossible. Yay!

As an aside: I had never heard of MailWasher before seeing a reference to it in a recent column in our Houston Chronicle - from what little I've seen, it's going to make a HUGE reduction in my mail processing grievance index!
David Jenkins
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Re: Newbie Question

Tue Dec 21, 2021 4:33 am

Forgot to add: The general subject of email validation is very interesting. Regex validation of email addresses (and phone numbers, for that matter) is way more complex than at first blush. You might be interested in the article found here: https://www.regular-expressions.info/email.html .
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rusticdog
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Re: Newbie Question

Thu Dec 23, 2021 2:04 pm

That link might be where I got the guts of that expression from :) It does get horribly complicated, I like to rely on a simple more generic expression, although not 100% it catches the addresses I need.

If you care for such things, the engine we use is Deelx http://www.regexlab.com/en/deelx/syntax.htm
They also have a utility program http://www.regex-match-tracer.com/ if you do want to construct/test expressions, though most online ones work the same.

MailWasher also has case sensitivity turned off by default.
David Jenkins
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Re: Newbie Question

Thu Dec 23, 2021 3:33 pm

Thanks.

I'm a huge proponent of regexes, as you can tell. In the past, I used RegexBuddy to test and develop expressions (same developer/company as PowerGrep). Great product.

Question: When MailWasher examines a FROM address using a regex filter, is the FROM string delimited on the right with any particular character?
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rusticdog
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Re: Newbie Question

Thu Dec 23, 2021 8:36 pm

If I understand the question, then no. MailWasher will take everything after the "FROM: " for checking.
David Jenkins
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Re: Newbie Question

Fri Dec 24, 2021 3:04 am

I guess I was really wondering if I needed to include '^' and '$' to make sure that the regex matched the entire FROM string, but now I see that MW provides an 'IS' match option, which I infer means that the entire FROM (in my case) string has to match. I was thinking that I might have to include a '\n' or something to make sure that I could get it to do what I want.

Example: I want to remove mail where the FROM address is (let's say) a string of letters, followed by an '@', followed by another string of letters. I do NOT want it to match: 'ABC.DEF.com' but I DO want it to match 'ABC@DEF'.

I get a lot of spam mail where the FROM address does not include a suffix, and I'm just trying to weed those out.

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