understanding Verifier / BounceHandler discrepancies

[fabprog]

I performed a mailing last week and I carefully collected bounces and compared the results returned by Bounce Handler with the results obtained by submitting the same email addresses to email Verifier, obtaining a weird mismatch so may be there's something I'm missing / I still did not understand.
Exact numbers follow:
- emails sent: 3160
- wrong addresses returned by email bounce handler (thats is, hard bounces marked as red with exclamation mark): 58
- wrong addresses returned by email verifier (the ones marked as red): 39
1) addresses retrieved as wrong (red) by bounce handler that are NOT marked as wrong (red) by verifier: 46
2) addresses marked as wrong (red) by verifier that are NOT in HARD bounces (marked as wrong, red) retrieved by bounce handler: 27
3) addresses marked as wrong (red) by verifier that are NOT in ANY kind of bounces retrieved by bounce handler: 13

Although point 1 could be explained (I guess) by some servers not responding/collaborating with the Verifier, so that Verifier can't be sure about them, I have no explanation for points 2 and 3: why does Verifier return as wrong some addresses that did NOT originate any kind of bounce after sending???
Should I trust Verifier and remove them anyway??
(side note: I waited more then 72 hours before scanning for bounces so I shouldn't have missed anything)

 

[stanbusk]

2) addresses marked as wrong (red) by verifier that are NOT in HARD bounces (marked as wrong, red) retrieved by bounce handler: 27

Verifier marks it and retained what the server said about that address, did you read it?

3) addresses marked as wrong (red) by verifier that are NOT in ANY kind of bounces retrieved by bounce handler: 13

Same here, why Verifier marked it, what was the server response?

About #1, you actually found the reason why.

 

[fabprog]

the server responses reported by the Verifier (for first and second group referred above) follow:
(sorry installation is in Italian)
(note I removed the first report column containing email address)

Tipo di Email Risposta del Test Risultato del Test Commento
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Commerciali 550 Requested action not taken: mailbox unavailable or not local Sbagliato Indirizzo sbagliato
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 550 <[email protected]>, Recipient unknown Sbagliato Indirizzo sconosciuto
Italia 421 4.7.1 Intrusion prevention active for [79.17.130.32][D] Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 550 Requested action not taken: mailbox unavailable or not local Sbagliato Indirizzo sbagliato
Italia 550 RCPT TO:<[email protected]> User unknown Sbagliato Indirizzo sconosciuto
Italia 550 RCPT TO:<[email protected]> User unknown Sbagliato Indirizzo sconosciuto
Italia 550 RCPT TO:<[email protected]> User unknown Sbagliato Indirizzo sconosciuto
Italia 550 RCPT TO:<[email protected]> User unknown Sbagliato Indirizzo sconosciuto
Italia 550 RCPT TO:<[email protected]> User unknown Sbagliato Indirizzo sconosciuto
Italia 550 No Such User Here","Sbagliato Indirizzo sconosciuto
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Commerciali 550 Requested action not taken: mailbox unavailable or not local Sbagliato Indirizzo sbagliato
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront1.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Commerciali 550 <[email protected]> No such user here Sbagliato Indirizzo sconosciuto
Italia 550 <[email protected]>, Recipient unknown Sbagliato Indirizzo sconosciuto
Italia 421 4.7.1 Intrusion prevention active for [79.17.130.32][D] Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront1.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 550 <[email protected]>, Recipient unknown Sbagliato Indirizzo sconosciuto
Commerciali 421 Service Temporarily Unavailable Sbagliato Casella di posta disattivata, non accetta messaggi
Commerciali 550 No such user ([email protected]) Sbagliato Indirizzo sconosciuto
Italia 421 <[email protected]> Service not available - too busy Sbagliato Casella di posta disattivata, non accetta messaggi

Tipo di Email Risposta del Test Risultato del Test Commento
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront2.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 421 4.7.0 mailfront1.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 550 <[email protected]>, Recipient unknown Sbagliato Indirizzo sconosciuto
Italia 421 4.7.0 mailfront1.interhost.it Error: too many errors Sbagliato Casella di posta disattivata, non accetta messaggi
Italia 550 <[email protected]>, Recipient unknown Sbagliato Indirizzo sconosciuto
Commerciali 421 Service Temporarily Unavailable Sbagliato Casella di posta disattivata, non accetta messaggi

 

[stanbusk]

Error 421 is a soft error, it means a temporary error.
Error 550 however is a hard error, it means the address no longer exists.

Sending an e-mail to an address that caused a 421 error may work.
Sending an e-mail to an address that caused a 550 error will not.

 

[fabprog]

ok, so I finally understand that not ALL addresses returned with test result = "wrong" by verifier are really necessarily wrong: only 550 are (may some other error codes too, don't know which ones).
So "wrong" means that something went wrong with the test, NOT that the address itself must be wrong.
If I'm right, please may you list the (only) server codes returned by verifier that guarantee the address is certainly wrong and can be removed? (if others exist in addition to 550)

 

[stanbusk]

Hard errors are all the 5xx errors. They means the address is bad, doesn't exist, has been deactivated...etc...

Soft errors are all the 4xx errors. You can receive such errors even when the recipient mailbox is full.

In eMail Bounce Handler you can set an address as bad when you receive more that a given amount of soft bounces.

 

[fabprog]

I recovered this thread after some time because I performed some testing after sending a mailing.
I discovered some recipients returning test result = wrong by email verifier with the following test answer templates:

550 RCPT TO:<[email protected]> User unknown
550 <[email protected]>, Recipient unknown
550 Requested action not taken: mailbox unavailable or not local
550 <[email protected]> No such user here

that did NOT originate a hard bounce!
Reading the previous posts above, I understood that 5xx test codes should always imply a hard bounce either.
However these recipients originated a soft bounce retrieved by the bounce handler, reporting the following:
kind of bounce = 'soft'
reason = "stato non definito del sistema di posta" (strict English translation would be: "undefined state of mailing system")
Should I better delete even recipients originating 'soft' bounces but returning 'wrong' test result (as reported in the message templates above) by email verifier? (since these 'soft' bounces at the end seem non to be that "soft"..!)

 

[stanbusk]

But what do you get in the eMail Verifier console for that recipient?

 

[fabprog]

Three template extracts from verifier log file, for given recipients:

[03] 10/27 15:46:47 550 RCPT TO:<[email protected]> User unknown

[05] 10/27 15:46:08 250 Requested mail action okay, completed
[05] 10/27 15:46:08 > RCPT TO:<[email protected]>
[05] 10/27 15:46:08 550 Requested action not taken: mailbox unavailable or not local
[05] 10/27 15:46:08 221 Service closing transmission channel

[06] 10/27 15:47:37 550 <[email protected]> No such user here

 

[stanbusk]

The three are hard bounces. First and last show clearly the address is not valid. Second one is unclear. This is what I see here.

 

[fabprog]

That's why I posted. Remember the three given examples were returned by email bounced handler as SOFT bounces! Maybe the default rules discriminating hard and soft bounces are not perfectly shaped and need some changes...

 

[stanbusk]

Have you added new rules? Default rules don't affect those addresses.

 

[fabprog]

mmm... maybe, I don't remember sincerely.
I added one custom rule for detecting complaints. I don't remember if I altered or added any other rule in the past, but it could be.
Consequently I have two questions:
1) how to check if I added/changed any rules I don't remember any more? Is it ok comparing the set of rules I'm using (shown under the "rules" tab in the main windows) with the rules in the preferences panel after restoring the default rules in the prefs?
2) In the rules panel I can see all the active rules and their triggers: but how can I tell whether a rule generates a hard or soft bounce?

 

[stanbusk]

1) how to check if I added/changed any rules I don't remember any more? Is it ok comparing the set of rules I'm using (shown under the "rules" tab in the main windows) with the rules in the preferences panel after restoring the default rules in the prefs?

Yes, the only way is to check those rules.

2) In the rules panel I can see all the active rules and their triggers: but how can I tell whether a rule generates a hard or soft bounce?

Rules generate only hard bounces actually.