e-mails not always received - are being rejected to sender
This is a periodic problem. Sometimes e-mails are received with no problem and then for the same e-mailer the messages are rejected back to sender
Alle antwurden (1)
First off Thunderbird has no mechanism to reject emails. It downloads email that make it into your inbox on your email providers server. If the messages are being rejected by the providers server then you need to address this with them.
The sender should be getting a reason for the rejection. That would be a clue to what is happening.