Sent emails reach the recipient but are not saved in the Sent Items folder.

Try checking Tools -> Account Settings -> Copies & Folders for the account and check to see that under When sending messages, automatically - Place a copy in is checked and set to something. Mine are set the Sent folder of the particular account.

It’s the same for me.

Is your account configured as IMAP or POP? What mail provider? Do you scan your email with an antivirus?; Which one?

Is your account configured to work via the IMAP or POP protocol? IMAP Which email provider? yandex.ru Do you check your email with an antivirus? Which one? The provider provides the check.

Please Check this again - but this time select the 'Other' option so you can specify the 'Sent Items' folder.

• Tools -> Account Settings -> Copies & Folders for the account
• Select: 'Place a copy in'
• Select: 'Other' and choose 'Sent Items in yandex email address account'

Exit Thunderbird - wait a few moments for background processes to complete Start Thunderbird.

Please report back on results.

Thanks! It helped. There’s another problem: when printing from Thunderbird, a white sheet comes out. Can you help with this? Thank you in advance!!!

Thanks! It helped. There’s another problem: when printing from Thunderbird, a white sheet comes out. Can you help with this? Thank you in advance!!!

Sorry for delay, I've been checking out bug reports.

This issue was indeed reported as a bug. https://bugzilla.mozilla.org/show_bug.cgi?id=2066228

The bug was reported several times, but this is the bug report that says it should be fixed. https://bugzilla.mozilla.org/show_bug.cgi?id=2057444

But it is only recent fix. I'm not sure what version you are currently using, so maybe you are using a version that will soon update to a fixed version.