ok, this can be fixed ' - if thunderbird is accessible, click help>troubleshootinginformation - scroll down to profile folder in left sidebar and then click open folder - then exit thunderbird - open the file called prefs.js with a simple text editor, such as notepad - look for that change that you made. it probably begins with 'layout' and you will see the value you entered - change to a more reasonable number and save and restart thunderbird

If thunderbird is not usable due to font size, then do it this way - with thunderbird not running, in search box in task bar, enter %appddata% and press enter - if it lists choice of local or remote, click to remote - click then thunderbird folder and then the profiles folder - your profile is here. if more than one, look for the one with current dates - click there and follow above instructions for prefs.js

TIP: if your concern was on font size of messages, there are cleaner ways to do this.

Thank you very very much David, I really appriciate your help.

Your solution worked for me within 2 minutes. Today I found the settings to be 12.2. instead of 1.2 in the prefs.js file. Actually I was looking for some kind of .ini file yesterday, but was not able to locate any like the above.

I really made a crazy mistake very late before going to sleep. Never try such things when it's late and feeling sleepy.

Thank you again - I am so thankful now.

Best regards Alex

My problem from the start actually is the font size. At my work we are using Outlook. In outlook you can chose the fontsize directly to be 12, 14, 16 and the program remember your zoom settings and font size.

I have specified the font size for outgoing messages in my TB to be 12 - but compared with outlook the text is very small and very difficult to read writing a new message. I can keep the font size, but I would appreciate if there is some kind of possibilty to keep the zoom I have chosen.

When sending a mail to my work mail, the font size is 12 and it looks fine when reading in outlook.

If you have any good ideas to keep the zoom when editing messages and the zoom is the same after closing TB and start again - it really will help a lot :-)

Thank you again...

Best regards Alex

I have complete instructions at this post:

 https://support.mozilla.org/en-US/questions/1437527     

There are multiple steps, but they do work. Remember that thunderbird uses points, not pixels, so I encourage starting with a number a bit higher than you're used to. That is, if you like a font size 12, try 14 to see how that works, and change if needed. Look at the attachments carefully. They are all for calibri 14 and that is not a large font. The instructions also emphasizes NOT relying on HTML for the font size. That encourages that people receiving your messages will see in their own font and in their own desired font size. If you have problems, be sure to post screenshots of the settings .

Thank you again David Sorry for not adding the images.

I have tried to follow all the steps described When changed all the settings it seems to have no effect to make the fonts bigger. I have used all the sizes suggested and the font type as well.

But the font of the received mails and when editing af mail to be send, the size seems to be equal.

Unfortunately the font size is very small both places - when writing mails and the recieved mails. As you can see in the picture with the large font - this was how it looked before I made the changes according to the link you have informed.

Is there any possibility to make the size larger? Please take a look in attached pictures for both when writing a mail and the one received?

Best regards Alex

Please post screenshots of the panes where you changed as shown in examples here:

Hello David, I really appreciate your patience in finding a solution for me. As far as I can see - the settings should be like yours.

I am attaching my photos. As I am Danish, I use TB in the Danish language.

Best regards Alex

Remember, these are points, not pixels. Try 20 for all the numbers and see how it looks. And a reminder: this only applies to how messages appear to you. Recipients will see however their email client is configured.

Hi David, Yeah I read about the information about pixels/points before. After your suggestion, changing the numbers to a higher value, it did help me a lot. And I am very thankful that it does not have any effect on the mails send to my contacts.

No I clearly can read the text I am typing.

What is the reason that you need to change the values so many places in TB? I would never have known how to solve this without your support?

But I guess that here probably is a idea about that?

Best regards and thanks again for this very helpfull support.

I'm glad all is working. I believe the multiple settings are because Thunderbird can support multiple character sets. I find that setting both of those ensures that the font size you see when composing is the same one you see in sent folder. And you are very welcome.