Am being plagued by spam e mail messages whereupon the text within the E Mail "subject" is created using double underlining. This method is impossible to duplicate when creating a filter due to the fact that the browser (Firefox) does not have the capability for formatting text and (to add insult to injury), the double underlining is applied to individual letters and spaces within the subject - very devious and effective of the author!
One could use a text editor or an office based word processor to duplicate the offending text with the double underlining but copying same across to the VM filter doesn't preserve the formatting, sigh.............!
Whoops! Apologies, I made an error in the original, I.e. the phrase "subject" should have actually read as: "from".
Anyhow (believe it or not) the solution has presented itself - out of the blue. If you receive a spam e mail which uses double underlining in the "from" section of the mail and you wish to create a bespoke filter within your VM Webmail account.
Within your usual e mail client, (whichever you are using - for me Thunderbird). Simply go to reply to the offending message and (when it opens) you should see the double lined text within the body of the original message - usually at the top. Highlight, then copy the double underlined text and then cancel the reply.
Within VM Webmail, create the new filter then (from the parameter down list within the filter) select - from. Paste the saved text into the "from" filter and the text formatting should be maintained, for example (of a recent spam e mail I received) C̳o̳n̳f̳i̳r̳m̳a̳t̳i̳o̳n̳_̳N̳e̳e̳d̳e̳d̳. Note you could also add @'s (wildcards) within your filter for greater filter flexibility.