From the View menu, select Zoom->Reset to reset the text size to the default. Alternatively you can press the Ctrl and 0 (zero) keys simultaneously.

If the text is still too small for you, it can be made larger by selection View->Zoom->Zoom In from the menu or pressing Ctrl++.

Further detail: This problem suddenly noticed yesterday, message printed out about 1/40th of normal. Pasted message to a MS WORD doc, and it printed normal size. Same fault this morning, checked the error console to find (just with today's date!) about 80 warnings, about 20 concerning fonts, and 3 errors, 2 on fonts, including: Error: downloadable font: kern: Too large subtable., table discarded (font-family: "Open Sans Light" style:normal weight:normal stretch:normal src index:1) source: https://mozorg.cdn.mozilla.net/media/fonts/OpenSans-Light-webfont.1c8075cacedb.woff.

Using Thunderbird on Acer laptop, Windows 10. Has been working perfectly. Suddenly whenever I try to read an email the font is tiny - so tiny it can't be read. I tried turning Thunderbird on and off - also restarted the computer - it didn't help. I want a permanent fix so I don't have to zoom in manually every email I look at.

No change after using zoom reset. This doesn't seem like a zoom fault because visually on screen there's no abnormal indication, and the zoom has a normal effect on the screen image; only the printout is abnormally small.

Attached is a composite put together to display the fault. It shows a "standard" printout of a Microsoft email that's about 1 1/2 pages long. The printout page header and footer seem about normal, maybe 10 pt., too close to page top and bottom but readable, whereas the rest of the message is jammed up into the top 4 cm., illegible. The print is not always centred on the page like this, probably a setting I've played with. Then to make it easy to compare the two views, I took a screen print of the Thunderbird view, printed it actual size mid-page, and scanned the full page. That scanned composite is attached.

re :Suddenly whenever I try to print an email the font is tiny. your image explains this clearly.

Try this: select the email so you can see it in the lower Message pane.

File > Print Preview or Menu icon > Print > Print Preview

At the top you should see a 'Scale' option. Increasing the scale will increase the font. when it fits the page more to your liking then use the 'Print' option.

note: if you only want to print a section of the email: Highlight that section in the email and then select the Print Preview option. This can be useful when receiving some emails that have a load of extraneous bumpf which you do not want to waste a load of paper on printing.

singer35 You have completely different issue. You do not talk about a problem where the email itself is perfectly ok, but the printing is not ok. This question specifically relates to only a printing issue. Please create a new question and someone will assist.

Reread Organic's original problem, looks like mine, Singer35, and so I don't see why your second message is so curt. Clearly you know more than I do, so I'll try again.

Apologies, Singer35, in retrospect I see ToadHall is on edge over something, not you.

Geoffoh re :Reread Organic's original problem, looks like mine Yes, your printing issue is the same as Organic and so the answer I gave should help you both get the font size much better for a print out. It does not effect the size of the font in the actual email. Did you try the 'Print Preview' and use 'scale' to increase the font so it uses more of the page?

re :in retrospect I see ToadHall is on edge over something I've just offered information for you to try. Some polite feedback would be more useful to everyone.

The second message as you can see was not directed towards you, but was instead a useful piece of advise for Singer35 who has a different issue and needs to get it resolved.

the curt message was not mine. However, he is correct, my problem is different