Does using safe mode help? https://support.mozilla.org/en-US/kb/safe-mode-thunderbird I looked comments from one month of crashes and almost none are English locale. So I have to wonder whether this is language related. https://crash-stats.mozilla.com/signature/?product=Thunderbird&signature=OOM%20%7C%20large%20%7C%20mozalloc_abort%20%7C%20mozalloc_handle_oom%20%7C%20moz_xmalloc%20%7C%20XPCConvert%3A%3AJSData2Native&date=%3E%3D2018-01-05T11%3A44%3A50.000Z&date=%3C2018-02-05T11%3A44%3A50.000Z&_columns=date&_columns=product&_columns=version&_columns=build_id&_columns=platform&_columns=useragent_locale&_sort=useragent_locale&_sort=-date&page=5

It crashes in safe mode too. The first crash happened when I was just clicking on an e-mail. After that it was just impossible to login. Each time I start Thunderbird it asks for the pwd and when I am typing it crashes.

Can you try the beta at http://www.mozilla.org/thunderbird/channel/ ?