Try setting

plain_text.wrap_long_lines

to true.

Personally I prefer to use format=flowed and let the lines wrap dynamically. Setting a fixed length leads to a mess when quoting and re-quoting, and your line length may not suit another user or their device.

This does not work; I already posted my settings above which have plain_text.wrap_long_lines set to "true". Here again are my settings, they where hard to read because line breaks were removed...

Edit -> Peferences -> Advaced -> Config Editor... reads

view_source.wrap_long_lines = true

plain_text.wrap_long_lines = true

mailnews.wraplength = 72 (default)

mail.wrap_long_lines = true (default)

Re "Setting a fixed length leads to a mess when quoting and re-quoting":

Are you saying that ThunderBird cannot handle mailing lists appropriately?

When I am reading mailing lists, I come across correctly quoted (and correctly re-re-re-re-quoted) messages, so I wonder how to achieve that?

These issues are puzzling. Every so often, someone will report that his lines go off indefinitely to the right and yet we fail to find any settings amiss. Often this is in incoming messages and we think this is a problem at the composition end. Some mail clients don't use regular spaces between words, and Thunderbird doesn't know that the non-standard characters used instead represent line break opportunities. It's as if everything was composed using   characters between words. e.g.

Some mail clients don't use regular spaces between words, and Thunderbird doesn't know that the non-standard characters used instead represent line break opportunities. It's as if everything was composed using   characters between words. 

And then a few report this happening when composing too.

Your report is rather different in that you say it wraps (or flows?) when you compose but it goes awry at the recipient. Is that when viewed in Thunderbird, or do you know if it's happening in other clients? (I use two other newsreaders, Pan and Groundhog, and neither behaves satisfactorily when handling quoted material. And a Thunderbird user on the newsgroups frequently laments about his unhappiness with Thunderbird's treatment of format=flowed.)

If you adjust your composition window to be very wide, does the text flow to fit it, or does it fold at or around column 72?

I think flowing the text and having it auto wrapped at a specified column is OK. But a few users work as if they are using a typewriter and manually hit return at the end of each line. They are then sending lines of fixed width and in being quoted and requoted start to behave like this:

> > > > I think flowing the text and having it auto > > > > wrapped at a specified column is ok. But a > > > > few users work as if they are using a > > > > typewriter and manually hit return at the > > > > end of each line. They are then sending lines > > > > of fixed width and in being quoted and > > > > requoted start to behave like this. > > > >

Two more setting options to look at. What settings do you have for these two?

mailnews.send_plaintext_flowed mailnews.display.disable_format_flowed_support

Ok, understood: This is impossible to solve, and trying to improve the situation will it make even worse... At least with ThunderBird. I am still wondering how other eMail clients make this work, so it's definitely worth a try.

Thanks for your help.

FYI, I sent a test mail with a long line to myself. The text appreared to wrap correctly with TB when composing. I also used TB to read and display that mail, but it was one gigantic line of text (using usual word lengths).

If TB was using &nbsp when composing, then the virtuall line wraps would not work I think.

Could you post me one of these? I'm curious to see if there is anything specific going on that is reproducible.

xenos at gmx dot co dot uk