The original email contains html css information. It was created that way by whomever sent it to you.

When you 'forward' the email and then try to type your comment, the font of what you are typing is being controlled by the html css code contained in original email section.

You could see if the following helps. Menu app icon > Options/Preferences > General Under 'Language & Appearance' Fonts & colours section click on 'Advanced'

fonts for: select 'Latin' Minimum font size: select 12

then you must for same - 'fonts for: select 'Other writing systems' Set the Minimum font size to 12

click on OK Restart Thunderbird.

Test to see if the minimum font manages to override whatever minimum font has been set int he email.

That is not the problem.

The problem is the appearance of the original email, whose format is defined by it's own css, is changed.

I'm not adding any comment.

The suggestion had no effect on the issue, but thanks.

Is the original email coming from office? I have filed a bug where Thunderbird displays fonts differently in the composer to what is send based on text pasted from office to Thunderbird,

I doubt it. It comes from eBay.

Tests on different Thunderbird versions. I located one email that seems to display an issue with font size.

Test in version 68.12.1 I notice some difference between 'Message Pane' and 'forward as inline' or 'Reply' display in Write window for some emails that used MSO, but the saved draft as viewed by Message Pane was correct again. Edit draft in Write goes wrong again in display for certain parts of text. Weridness abounds.

Tested again in Thunderbird Safe Mode and no issues at all, so I have a setting causing this oddity. Not in userChrome.css nor userContent.css - both disabled same issue. Removed 'Mail Merge' and any addon that was no longer compatible - no change. Disabled all addons remaining - lightning, signature switch and ImportExportTools - after restart no change - still have problem. mmmmmmmm!

In 'Options' - Cleared cache. Exited Thunderbird deleted panacea.dat, session.json, xulstore.json and the global-messages-db.sqlite files. restarted and tested.

The Message Pane display is now the same as the 'forward inline' - so in that respect it is ok. However, the Message Pane is where the change has occurred, not the other way around. This leads me back to the Options for Fonts for settings. Now that the data stored has been cleared

I can now influence what is displayed in the Message Pane, but it is done through the Fonts for: 'Other Writing systems' settings where I deliberately set all the font size options to 20. This can change what is displayed in the Message Pane and deals with MSO trying to influence the display. So it can appear larger font if required in Message Pane. BUT if you try to Reply or Forward, then the mso html css settings take control and you see a much smaller font size. That font size matched a 14pt which I had set up in settings for Latin despite the 'Other Writing System' settings on 20. But according to the email source view should have been an 18pt. So, something is not reading the mso settings correctly.

Tested email in version 78.11.0 The Message Pane shows that 18pt font as 18pt. The 'Write' window containing Forward as inline/Reply is correct - looks same as Message Pane and font looks like 18pt. So not seeing same issue. Nothing is wrong. Email font looks like an 18pt in both Message Pane and REply/Forward. My text in content is as expected size 14.

Updated Thunderbird to 78.12.0 as all is still ok.

Note: all settings are identical. Light theme on the 68 and dark theme on 78

Suggestion to see if you have something stored somewhere that is causing a problem. Check settings - I know you were in this area before, but make sure this time all font sizes are either a 12 or 14 depending upon your preferences.

Menu app icon > Options/Preferences > General Under 'Language & Appearance' Fonts & colours section click on 'Advanced'

fonts for: select 'Latin' For all the 'font size' settings - select 12 (or 14 if you prefer a little larger)

then you must for same - 'fonts for: select 'Other writing systems' For all the 'font size' settings - select 12 (or 14 if you prefer a little larger)

click on OK

In same area - Menu app icon > Options/Preferences > General 'Network & Disk Space' section Sub section 'Disk Space' Clear the cache - click on 'Clear now'

Menu app icon > Help > Troubleshooting Information Under 'Application Basics' - 'Profile folder' - click on 'Open folder' window opens showing contents of profile name folder.

Exit Thunderbird now - this is important.

delete these files:

• global-messages-db.sqlite
• panacea.dat
• session.json
• xulstore.json

Restart Thunderbird.

Is there any difference between the 'Message Pane' view of original email and the version when you click on 'Reply' or 'Forward'  ?

Thanks for the thorough and detailed response.

The problem only happens on the received forwarded email. The view in the message pane and forward composition window is correct. The recipients of the forwarded email are both using Thunderbird an I am also using it to send it.

I tried a forward to my gmail account and the fonts were tiny there too. The underlying use problem is the email contains important information that requires action and the recipient is unable to read it.

However, I did follow your suggestions and it made no difference.

I tried to compare the original and forwarded email sources using Winmerge but the differences were so great that with my limited knowledge it wasn't obvious where the problem lay.

re :I tried a forward to my gmail account and the fonts were tiny there too.

Are you reading that forwarded email in the gmail webmail account or via a gmail account in Thunderbird ?

re :The recipients of the forwarded email are both using Thunderbird

Do they both use a gmail email address ?

Does that particular 'forwarded' email contain anything too personal? I was hoping you could 'forward' that same email to me to both of the following email addresses - note I've written them phonetically to avoid bots, eg: where I say 'at' it means @

• mail at anje dot co dot uk
• anjeyelf at gmail dot com

Received email at first address. Email looks ok.

However, if I select Fonts for: 'Other writing Systems' Set Minimum font to 'None'

then a large section - all the first part - in fact everything before 'Order number' is now unreadible using font size of 1px.

Looking in Source View It has been created using microsoft office there are lots of references to mso. It is a bit messy to put it politely with loads of unnecessary tables and most of the rows have been set with a style setting of font size set to 1px, which seems to override the paragraph settings in that section.

So it would seem that font size setting is messing up the view, but I am only able to replicate this by choosing no minimum font size - set to none as mentioned above. So that 'Other Writing Systems' can influence anything you get which has been written using MSO.

I suggest you see if it looks any different if you change the 'View' > 'Message Body as' > to 'Simple HTML'

Just sent to second address too.

Simple HTML does make it readable so there's a handy workaround.

My minimum font size is set to 12 rather than none. It remains a curiosity when this works on your set up and not mine. I have a linux machine too and exactly the same there.

Appreciate all your efforts and suggestions, Toad-Hall. Thanks.

12 pixels is pretty tiny. Especially in a high resolution monitor. Generally speaking about 60% of something of 12 points. /but with pixel doubled displays the change is huge.

The units for the font size are not specified in the options dialog.

You seem to me implying that the units are pixels, not point. That would be surprising and unusual. As far as I can see the help is silent on the matter. But then I'm straying into another gripe and that is the lack of user guide.

In the email you forwarded to me, all references to the font size are in px (pixels). A variety of sizes are used ranging from 15px. 18px and 20 px. But in some rows they have used 1px and there are a lot of them. If you set the 'Other Writing System' option to 'none' or a low setting then this is causing it to mess up the view to an extreme creating some very small font size.

Most people are not aware that the Fonts for : 'Other Writing System' effects emails written using MSOffice.

Thunderbird 'font size' references in the settings via Options/Preferences are in pixels.

Pixels are smaller than Points. Many people maybe used to using Point in MS Word when you set a size of 12, it is refering to points not pixels. But the email MSO html css settings are in pixels.

The screen resolution on computer is in pixels and so this can also effect the display as not all people use the same resolution meaning a pixel in itself can appear to be a different size. The more pixels you have per inch/cm, the smaller the pixel. So it can be somewhat confusing. Hence why some people can read in a set size and others cannot. It is a question of understanding what your computer screen resolution is offering and adjusting everything to suit your eyesight. Which is why it is easier to control if you use pixels.

This is also the reason why Thunderbird uses a 'Medium' setting when you compose a message, relates to whatever you have set up as your 'font size'. So a Medium font size on your computer might show as a 12 pixel, but if you sent that message to me, my 'Medium' settings would change it automatically to display as a size 16 pixel. It means it can easily adjust for each person and use their settings.

It gets awkward when people try to force an explicit font size on people and include it in the html css of an email. Just because it looks good to the person creating it does not mean it will look good to another person. We all have different screen resolutions and eyesight.

A guide in points and pixel size: Points = Pixels 6pt 8px 7pt 9px 7.5pt 10px 8pt 11px 9pt 12px 10pt 13px 10.5pt 14px 11pt 15px 12pt 16px 13pt 17px 13.5pt 18px 14pt 19px 14.5pt 20px 15pt 21px 16pt 22px 17pt 23px 18pt 24px 20pt 26px 22pt 29px 24pt 32px 26pt 35px 27pt 36px 28pt 37px 29pt 38px 30pt 40px

Most people are not aware that the Fonts for : 'Other Writing System' effects emails written using MSOffice.

nor was I, but I guess they are still using the legacy ansi in Excel until recently. Do you know if it is all office or only pre unicode native versions or other specifics.