[MlMt] Search parameter "is" vs. "contains"

[Bill Cole]

On 2024-05-13 at 15:22:21 UTC-0400 (Mon, 13 May 2024 12:22:21 -0700)
Devyn Osborne <mailmate at lists.freron.com>
is rumored to have said:

> Hi All,
>
> I searched for this issue but it’s a bit tricky due to the common 
> words used.

"Is" means that the match needs to be complete and precise. You may note 
that when you select the "Is" menu item, the text field becomes a 
combination text box and drop-down which lists all of the values that 
exist in your mail.

"Contains" means that whatever string you enter can exist somewhere in 
the selected header field, even if there is more to that field.

> I’ve run into a curious result when creating search / smart mailbox 
> rules for the From address. Here’s what I’m seeing:
>
> - “From” “contains” “name at example.com” — this returns 
> the expected results (all emails from name at example.com)
>
> - “From” “is” “name at example.com” — this returns *zero* 
> results

Correct, because the "From" header always has more than just the sender 
email address. If you want to JUST match the address in a From header, 
you can select From->Address in the field menu and use 'is' instead of 
"contains".

> I know search rules can sometimes operate differently than expected, 
> due to the specific logic, but this one is curious to me. Why would a 
> “from is a specific address” not work? Is it because the 
> “from” actually looks to search like “Devyn Osborne 
> (name at example.com)” so is not solely the email address?

Precisely.

Standard email headers can have very complicated structures, but they 
are rigorously defined and so can be decomposed quite reliably into 
logical parts. The possible formats of the "From" header are 
mind-numbingly complex and some senders play games with that complexity.

-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo at toad.social and many *@billmail.scconsult.com 
addresses)
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