more strict junk checks for some first-time senders: when TLS isn't used and when recipient address isn't in To/Cc header

both cases are quite typical for spammers, and not for legitimate senders.
this doesn't apply to known senders. and it only requires that the content look
more like ham instead of spam. so legitimate mail can still get through with
these properties.
This commit is contained in:
Mechiel Lukkien
2023-11-27 10:34:01 +01:00
parent 8e37fadc13
commit 2ff87a0f9c
8 changed files with 69 additions and 19 deletions

View File

@ -574,21 +574,21 @@ func TestForward(t *testing.T) {
totalEvaluations := 0
var msgBad = strings.ReplaceAll(`From: <remote@bad.example>
To: <mjl3@mox.example>
To: <mjl@mox.example>
Subject: test
Message-Id: <bad@example.org>
test email
`, "\n", "\r\n")
var msgOK = strings.ReplaceAll(`From: <remote@good.example>
To: <mjl3@mox.example>
To: <mjl@mox.example>
Subject: other
Message-Id: <good@example.org>
unrelated message.
`, "\n", "\r\n")
var msgOK2 = strings.ReplaceAll(`From: <other@forward.example>
To: <mjl3@mox.example>
To: <mjl@mox.example>
Subject: non-forward
Message-Id: <regular@example.org>
@ -655,7 +655,13 @@ happens to come from forwarding mail server.
mailFrom := "other@forward.example"
err = client.Deliver(ctxbg, mailFrom, rcptTo, int64(len(msgOK2)), strings.NewReader(msgOK2), false, false, false)
// Ensure To header matches.
msg := msgOK2
if forward {
msg = strings.ReplaceAll(msg, "<mjl@mox.example>", "<mjl3@mox.example>")
}
err = client.Deliver(ctxbg, mailFrom, rcptTo, int64(len(msg)), strings.NewReader(msg), false, false, false)
if forward {
tcheck(t, err, "deliver")
totalEvaluations += 1
@ -1418,9 +1424,11 @@ func TestEmptylocalpart(t *testing.T) {
t.Helper()
ts.run(func(err error, client *smtpclient.Client) {
t.Helper()
mailFrom := `""@other.example`
msg := strings.ReplaceAll(deliverMessage, "To: <mjl@mox.example>", `To: <""@mox.example>`)
if err == nil {
err = client.Deliver(ctxbg, mailFrom, rcptTo, int64(len(deliverMessage)), strings.NewReader(deliverMessage), false, false, false)
err = client.Deliver(ctxbg, mailFrom, rcptTo, int64(len(msg)), strings.NewReader(msg), false, false, false)
}
var cerr smtpclient.Error
if expErr == nil && err != nil || expErr != nil && (err == nil || !errors.As(err, &cerr) || cerr.Code != expErr.Code || cerr.Secode != expErr.Secode) {