Failed sending email - Error Report

I just got an email from my LC store:

LiteCart 2.3.1

[27-Dec-2021 21:01:38 Europe/Warsaw] Warning: Failed sending email "[Not Found Report] mezeReina - biżuteria autorska" in ~/includes/entities/ent_email.inc.php (Line 388)  ← ~/includes/library/lib_route.inc.php (Line 145) in send()  ← ~/index.php (Line 40) in process()
Request: GET /doku.php HTTP/1.1
Host: www.mezereina.pl
Client: 148.153.51.249 (148.153.51.249)
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.125 Safari/537.36

Any ideas what that's about? The contact form in Customer Support page seds emails OK....

LiteCart failed to deliver the email of requests made to the platform that doesn't have a destination (404).

But what does that mean? :-) 😀
Should I worry about that or not? If so what can I do to fix that?
BTW Happy New Year 😁

Make sure that your platform can send emails. Configure SMTP if needed under Admin -> Settings. Change the recipient of the error reporter background job module if it's not valid. And happy new year :)

Hi, I'm back with more of the same. Check it out:

LiteCart 2.3.1

[25-Mar-2022 21:39:39 Europe/Warsaw] Warning: Failed sending email "[Not Found Report] mezeReina - biżuteria autorska" in ~/includes/entities/ent_email.inc.php (Line 388)

← ~/includes/library/lib_route.inc.php (Line 145) in send()

← ~/index.php (Line 40) in process()

Request: GET /.well-known/traffic-advice HTTP/1.1

Host: mezereina.pl

Client: 66.249.81.122 (google-proxy-66-249-81-122.google.com)

User Agent: Chrome Privacy Preserving Prefetch Proxy

I keep getting that kind of emails from time to time - once a month maybe. The funny thing is that the email sending function works - I test it every time I get such an error and the contact form and the order mesages perform ok - I get all the messages - order confirmation, order payment pending etc. 

What kind of email failure is this warning about?