I created a workaround. You can use the Stylish or Stylus browser extension and then install/apply the style from here: https://userstyles.world/style/19557/proton-mail-zoom-reading-pane

All this does is add a little CSS to the page:
.message-iframe > iframe {
zoom: 1.2;
}

That CSS will zoom the iFrame that the email is in. Bigger number is bigger zoom level.
I hope this helps.

I want to set the font/zoom size in the reading panel independent of the rest of the UI.
Currently I can read the UI just fine, but the text in emails is difficult to read.

When I zoom in, the UI also grows, but I just want the emails to be more readable.

The font size set to very large is still uncomfortably small. The page does not follow the browser zoom function for message text, so its difficult to read - one more vote to increase the font size here.

The fact that you can't really increase the font size is really disrespectful to the vision-impaired community. Not everyone is totally blind. Some of us just have poor vision. Come on, Proton!

Another vote for being able to zoom in or use a larger font for reading incoming emails. I am not really happy about the limited number of fonts in the Composer, but the size can be adjusted there. There seems to be no way to increase the font in the reading pane of incoming emails. Please, may we have this improvement?

I'd like the ability to change the default font size for all emails from 14 pt to something larger.

I'm confused on this one.

Aren't there already a choice of ~7 fonts as well as font size selection?

I am able to select a font and size and make it default (it even prompts me to set default). Sure they stuck to business fonts, but don't really need all the other fancy ones, from a functionality standpoint.

As for letter spacing, that is determined by chosen font, but does appear to be a bit narrower. They need to fix that and make it so it is in accordance with basically universal standards.

Adding mono, serif, and sans versions of fonts would be helpful.

I would like them to add the Liberation font series. I find them to be the best.

Can Proton provide an explanation why, after almost six years, it is still not reviewing this idea?

I find it quite odd to not let users decide on something as basic as font size and refuse to communicate about it as well.

The font size isn't the problem; it's the kerning. There isn't enough space between the individual letters/characters. In comparison to emails I receive from MS Outlook, I noticed that the words in my sentences appear so much more bunched together and cluttered. I suspect the issue stems from the typeface rather than the font size.

I prefer to read my email from my desktop but the font is so small I am forced to use my phone most of the time. PLEASE PLEASE let us ENLARGE THE FONT ON THE INBOX.

I love that my mail is now secure. But paying for an email service and not being able to read it comfortably is absurd. What am I paying for? This should be a simple fix that all would benefit from.

The ability to choose fonts of an odd numbered size would be beneficial. Outlook uses Calibri 11pt and it would be good to select this due to the popularity of Outlook.

Add ability to setup the default fonts (style, size and etc.) for the new messages or when you reply. At the moment the fonts selection and modifications are available at the time of creating a new message. It has to be done manually each time. It would be nice to have a default font configuration in the settings of the account which can be set to desired font settings once instead each time for each message.

Hi all, sharing this in the hope it may help others out there....

I did a few tests trying to find the closest equivalent to Calibri 11 in Outlook which is what I'm most used to. Seems the closest were:

Proton Helvetica 16 = Normal Helvetica 12
Proton Helvetica 14 = Normal Helvetica 10.5
Proton Arial 16 = Normal Arial 12
Proton Arial 14 = Normal Arial 10.5

Proton sets it default size to 16, which doesn't appear to translate to 16 in the real world. Now that I realise this, while it's not ideal, it's kinda more manageable.

In short, if you normally choose between Calibri 10,11,12 in Microsoft land (most people?), then you're probably best to go for Helvetica or Arial 16 or 14.

Please try it yourself on webmail, via outlook and on your phone. I'd be keen to hear if my numbers are the same for others.

The UI text on the iPhone mobile app is just very small and light, especially for those of us who need reading glasses. This is true even when the global phone font settings are set larger for accessibility. I can see that this has been an issue brought up by many users in the past that still hasn't been addressed. Please consider a function where either the UI font size adjusts with the global phone system settings or add in a feature where it can be customizable within the app.

is there a way that the fonts can be changed/modified and/or make the current font bold? In addition, can the font be increased in size? it is hard to read such faded/small print. Thanks

SHould apply to compose mode and incoming mail

The font size is absurd. Luckily it is also present in the trial version and I can look for another mail provider before I start paying.

This is seriously annoying. I've just discovered it after joining.

I paid the subscription for Proton Mail last month; however, had I known there was no provision for changing the default font, I would not have. I am getting complaints from recipients that when I use the iOS app (on which I cannot change the font size even on individual emails), they cannot read the text. This is a basic feature and every other mail provider I have used offers the ability to change font type and size. PLEASE GIVE PROTONMAIL USERS THE ABILITY TO CHANGE THE DEFAULT TEXT SO THAT IT APPLIES to EVERY EMAIL WHETHER USING THE WEBSITE OR APP.