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Strollin' around
Status: New idea

I often end up with strange font sizing issues when composing an email where part of my email are in a larger font size than others. To change the font of your email, you can only increase or decrease the font size through the designated buttons or by changing the paragraph format altogether.

In my opinion it would be better to just display a size selection dropdown menu, just like pretty much every other application, allowing you to just pick the required font size and apply it to the selected text.

Status changed to: New idea
Community Manager
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New member

I have set my default font to Trebuchet MS 12, but still, when composing I see all sorts of sizes, paragraph and body text sizes. Being able to select all my text and change to the above font would be much easier. What I see on my laptop is not necessarily going to be what the reader at the other end sees!

New member

Before posting here, I once more made sure the settings in my Thunderbird are as stated below, and sent an email to another address of mine to make sure it works as intended. And it did. The font and size I had used in that test email was/is Calibri 12 (pt.).

I cast my vote in favour of "daanl - Strollin' around" suggestion. I think It should have been part of Thunderbird from the get-go. Just my two-cents.

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david |Top 10 Contributor
30/8/22 4:35 AM  
Chosen Solution

OK, here goes: 

- leave settings>composition alone. It defaults to 'variable width' and medium font. Do not touch. Changing that forces the font and font size to appear in outgoing message, which you don't want.

- go to tools>settings>general and select your desired font (my examples are calibri, 11 pt).

- click Advanced [button] and notice the dropdown menu at top for language selection [Fonts for]. You want to set preferences for 'Latin' and for 'Other Writing Systems', one of those is likely showing already. Set [all] the fonts as you want them. Be sure to set Monospace font also, as that is really just 'plain text' font choice.

- repeat EXACTLY for the other language. That is, if you set for 'Other Writing Systems', then do the same for 'Latin', these two must match. If fonts seem small, start with a setting of 20 pts and adjust. You have to set BOTH to see how it looks.


So, using David's above instructions as a guide, in Settings>Composition under the subheading of HTML Style, Font and Size, I first clicked on the Restore Defaults button. 

Next, in Settings> General under the subheading of Language & Appearance (Fonts & Colours), I set my chosen Default font to Calibri and its font Size to 12. (You choose which default font and size you prefer to use.)

I then clicked on the Advanced button next to the font Size (which I had changed to Calibri 12), and using the now showing Fonts & Encodings selection screen, below are a couple of images showing how I have set my  Latin page and Other Writing Systems page:

Latin page


Other Writings Systems page


I hope the above method (hopefully just a temporary workaround) may be of help in the setup of one's Thunderbird, so that the font and size one uses in the Composition window will be the same font and size in the Draft folder, and once sent, also the same font and size in the Sent folder.  And - though it depends, see below - it quite possibly may also be the same font and size to the recipient (the person to whom you are sending the email).

It should be noted that, to the recipient the message you send may look different, regarding the font and/or size. How it looks (font and/or size) depends on whether the email program which the recipient is using is itself set to use a different font and/or size of messages it receives. But no need to sweat about that part because it is outside your control. 😉

Making moves

I'm mainly hoping for formatting that's less prone to wild errors. Often, paragraph spacing changes for no reason - or in a way that makes no sense. At times, while I'm editing a message, I end up in a situation where I simply cannot insert a space - spaces simply disappear and my words run together. Lots more.

But aside from seeing those bugs eradicated, I'd love to see support for proper style sheets, based on standard CSS. Undemanding users should be able to install default 'stationery'. Advanced users should be able to create sophisticated CSS style sheets to get total control over formats.

New member

Seems to me that when get in a position with different font sizes it easier to save the email as a draft and finish editing with a different email program.

New member

Give back font size adjustment in received texts.  The standard is alt+ and alt-.  Why that was removed is beyond me.  Currently most received email texts are too small for reading.  This is a sufficiently serious problem so I would 1) give up supporting Thunderbird monetarily, and 2) stop using it if it isn't fixed quickly. 

New member

I have now used Thunderbird for many years, but am beginning to doubt whether it is a good solution. I don't understand why you don't make an option to choose the font size in a drop down menu. It is standard in all other e-mail clients i know of.  It is very difficult to be sure what an email looks like to the recipient, and that makes Thunderbird unsuitable for professional use, but also for personal messaging. What is foe you not introducing that option (is there a cost involved)? My request is that this should be put into place.

Familiar face

Lets look at this font size thing.

I see lots of folk here talking about using a number to specify a size.  Would that be in Pixels (the default for the internet and HTML and the numbers Thunderbird does use)? or points which is a rather abstract typesetters' measurement that has variously defined as the size of a point over the years as being between 0.18 and 0.4 millimetres and relates to putting ink on paper! 

With the advent of desktop publishing in the 1980s the desktop publishing (DTP) point became the de facto standard. The DTP point is defined as 1⁄72 of an international inch (1/72 × 25.4 mm ≈ 0.353 mm). Even now the point does not have an exact measurement and is based on a lineal measurement that is used in essentially about 4 countries in the world.

Many products you paste data from dospecify font sizes in numbers.  Onbe of the of the worst for that being Microsoft office, which pastes in the entire content of words and it's stylesheets to define the one line of text you pasted.  I have seen emails double and then double again in size when a single word is pasted from Micrisift office.  If you are getting odd font sizes, paragraph separation and other formatting issues, there are two workarounds that defeat this inadvertent copying of formatting data that goes with copying from other applications,  other emails and the web; 

  1. Copy the entire email body and then paste it back using the paste without formatting option. This will allow the base formatting you set in Thunderbird to function and take precedence over the odd bits that came from pasting
  2. Paste into Thunderbird using the paste without formatting option in the first place.

Fundamentally, Thunderbird uses a set of text literals to specify font sizes such as Normal and Large.  This is partially because while the internet uses pixels,  web browsers scale things to make them readable.  Generally, a browser uses 16pixels to 18 pixels to display unadorned text,  but these things are subjective.  Apple phones use a pixel doubling technology on their retina displays.  My phone (an android) and desktop computer with it's 24 inch monitor use very different scaling factors to make the text readable. The sizes I see are not all that different,  but they are not the same.

I certainly have no idea what the display characteristics of my readers choice of email platform will be using,  so setting the size of what they see as a percentage of an inch really is a rather inconsiderate,  if common practice.  Far better to specify "normal" text or "large" text and let the computers work out what "normal" is at the time of display.  Instead what we see if folk going out of their way to set a rather meaningless number because they think it will bring control and uniformity.  In terms of email, I believe that Microsoft and other in heading their users requests for this magical number have done us all a great disservice. Now we are forced to use the CTRL+ and CTRL- to manually scale emails because the sender made a size that suited them not the recipient, until they specified an inappropriate size, the machines worked it out automatically.