This study is garbage and I suspect there is some culture war bullshit going on here.

This is directly from the study:

4. Limitations and future work

This study had several limitations and was built on many approximations for which there could be errors. For example, the volume of email sent by richer nations like Canada would be expected to be much greater than poorer countries. In this way the calculations for the number of premature deaths would be underestimates because the Canadian fraction of the population would undercount actual email use. There are headers on emails that contain metadata that is sent with every email, which includes text with information, such as the sender, receiver, route, timestamps, addresses and more. Thus, even an email with no information if sent and opened there would be a transfer of data, energy used and thus emissions. This metadata was not considered in this study. The size of that metadata varies widely and the impact on these calculations is left for future work.

Future work can: More carefully quantify the impact of meta data on email emissions along with investigating ways to minimize this information. •Perform surveys to obtain more accurate values for Cp-e(x) and Cla-e(x) by obtaining more accurate values of the percent of the population that amends additional information to their email signatures. •More accurate values for the number of words most commonly used for pronoun identification will perhaps slightly improve accuracy from the 3 estimates used here, however such surveys will be far more important for the number of words used in land acknowledgements.

The carbon emitted per email will also vary with time and location based largely on what type of energy is used in the systems handling that email. More green grids will have a lower impact, while those that are powered with coal will have a worse impact. These can be carefully clarified with a granular future full life cycle analysis.

Finally, there is also clearly potential errors in the 1000-ton rule, as all the values going into it are order of magnitude estimates. It should be pointed out that there may also be life savings created by using pronouns in emails that may for example reduce suicide rates among transgender associated mental health issues. There is no evidence in the literature of this protective role of pronoun use available at the time of this writing. In fact, the greater public virtue signally in relation to transgenderism appears to be inversely proportional to considered and attempted suicide rates among transgender people in the U.S. over the last two decades [44]. It is not clear why this is the case, although based on the data available email signatures are expected to play an extremely small role in these rates in either direction.

These are huge limitations. The metadata in an email header is often enormous! Significantly larger than most land acknowledgements and several orders of magnitude larger than listing preferred pronouns.

On top of that, email signatures are typically only found on emails that are letter-style communications that have been sent manually by a person. I think it’s dangerous to assume that the bulk of emails being sent are in that category. I believe the vast majority of emails sent are marketing style messages, with embedded style-sheets, headers and footers, and links to images if not the images themselves. All of this adds up to far outweigh the impact of listing ones pronouns.

After saying all that, the author of the study persists in saying that the results represent useful guidelines.

With all of said the limitations of this study, the results of this study still provide useful guidelines for reducing environmental impact at the individual, firm, and national level. There are clear guidelines that can be given to email users to reduce the environmental and human impact of email use. In addition, by switching to a purely sustainable source of energy for our IT infrastructure and ensuring it is reusable/recyclable the impacts of email signatures can have a substantially reduced ecological and human mortality impact.

I am suspicious of the author and the website this is hosted on. Why would the author single out “pronouns” and “reputation signaling” as a problem here? They are claiming expertise in the area, but should know that they have picked a very small portion of a relatively small category of email. They are making claims about various numbers of people dying each year because of this “problem”. That’s a wild claim, designed to engage people emotionally instead of intellectually.