sorry, but sice I'm anti - f book, I write here!
I know the add-on from earlier and I was happy to discover it again!
...and then:

https://harakirimail.com/

The certificate of the remote station has expired.

HTTP Strict Transport Security: false
HTTP public key pinning: false

Certificate chain:

----- BEGIN CERTIFICATE -----
MIIEGTCCAwGgAwIBAgIQcfmNgXk6c0qJQc / fmM6yXjANBgkqhkiG9w0BAQsFADB7
MTgwNgYDVQQLDC9nZW5lcmF0ZWQgYnkgQVZHIEFudGl2aXJ1cyBmb3IgU1NML1RM
UyBzY2FubmluZzEcMBoGA1UECgwTQVZHIFdlYi9NYWlsIFNoaWVsZDEhMB8GA1UE
AwwYQVZHIFdlYi9NYWlsIFNoaWVsZCBSb290MB4XDTE5MDQwMzE2MTAwMloXDTE5
MDcwMjE2MTAwMlowGzEZMBcGA1UEAxMQaGFyYWtpcmltYWlsLmNvbTCCASIwDQYJ
KoZIhvcNAQEBBQADggEPADCCAQoCggEBAMQP6B3SmVjZu59ANxeFNnSpMGqaVXSS
ANqMYkrLyGrB7RIqcJurBbKl32kMfykaoW7GhhZyj0zc / 9KRYZVCcVkrcn2e9i23
LYpKlIkmujbrpCoXC8JvR4XetuPW9viwksFn / HpirSkDHEU92E42K9nz35azImPq
unMkvqrsvR8b + 1hclhxo6dlrEgsStTSNy1 / WQ0v1PhO6U59kQrZAWZCKca6vwqXN
91b2voBPow3ooC1zaKCnJjqWJpNvO7Cf6Tu4pUc3hoGmuPTnUGBLmGT1HJOzQrix
aQKI2X8TG0vq7MmP / q / 3opnoykb + 8Xe8F / XoRR85X0m93L4nnKkrVj0CAwEAAaOB
+ DCB9TAOBgNVHQ8BAf8EBAMCBaAwHQYDVR0lBBYwFAYIKwYBBQUHAwEGCCsGAQUF
BwMCMAwGA1UdEwEB / wQCMAAwHQYDVR0OBBYEFKANNDDKjF8J2BaTreSmKHnAhYyB
MB8GA1UdIwQYMBaAFKqaa + 5gAwIRvJ8kb2s / SclzPC3IMHYGA1UdEQRvMG2CFGFw
aS5oYXJha2lyaW1haWwuY29tghRkZXYuaGFyYWtpcmltYWlsLmNvbYIQaGFyYWtp
cmltYWlsLmNvbYIXc3RhdHVzLmhhcmFraXJpbWFpbC5jb22CFHd3dy5oYXJha2ly
aW1haWwuY29tMA0GCSqGSIb3DQEBCwUAA4IBAQBxTFEtEYAwep9WQZspWPyeHiJx
tqAqTb99FZt2rLwXXLOldPZR + C / GYgRrvkvtOTVeX51oR5W7fTlRXZ7MqTMpuNM /
EPus9IzdYkBxQZoBjveotKSFmvDGCbshlO / 3gWiBCoDPIbTckL3TTkzGo / TYKG / X
Uo03g4Zc3p1uhjwAypoJ0Jv ++ KpxIFYkdKvWAqYdeSfaNI8 / xQvfksbe9oxbzK2q
5BlCQFHpsgWt1 + c1lup / CJ28jaEuuOwoH + 9PN + + ZRuv 9IPkaZ / GBbFxHs2cxMj7q
+ JHA31bBUgIWeWwYZFZ0CnIYYq3Ar9G7g6ER1YQclaPZAAHSbwQebGHIUQtN
----- END CERTIFICATE -----

Very simple and easy to use. Love just right clicking and having a temp email created :)