There is nothing SpamAssassin related here. The information in the header is written w/ whitespace folding. Most MUAs leave it alone when showing it to you, Thunderbird apparently unfolds the lines.You may have an option which lets you disable it, but it's 100% a mail client issue.
ok. so far, googling, i haven't even found mention of the issue/problem, let alone a fix/option to turn it off. :-/ if anyone _here_ sees the problem in tbird, i'd appreciate hearing about it. thanks.
