'Mailbox Unavailable' Error Message

[bex1210]

I first did a search through this forum. Although users on other threads reported the same error message, none of their situations appeared similar to mine--hence this new topic.

My operating system is Windows 7 Pro (64 bit) SP1. My ISP is AT&T (Fiber). I use Thunderbird 60.0 (32 bit) as my Email program (which has not been updated since I installed it 10 months ago).

I have Email addresses at three providers. For this post, consider them to be myaddress@provider1.com, myaddress@provider2.com, and myaddress@att.com. I can also log into the webmail for each of the three providers at their website. I use IMAP, and my outgoing servers are SMTP.

A year ago, I moved my ISP from provider2 to AT&T. Shortly thereafter I installed Thunderbird.
I have one Email address at provider1, five at provider2, and one at att. My outgoing server (SMTP) for provider1 is their server. For provider2 and att, I use the att outbound server.

Up until a week ago, I could receive emails sent to any of my Email addresses, respond to those emails, or send new emails.

Everything still works for provider1 and att. I can RECEIVE emails sent to my provider2 addresses, but if I try to respond, or sent a new email from one of the provider2 addresses, I get this Thunderbird error message: "An error occurred while sending mail. The mail server responded: Request failed; Mailbox unavailable. Please verity that your email address is correct in your account settings, and try again."

Nothing has changed in my account settings-I checked. If I open my webmail account at provider2, I can still respond to emails, and send emails. So it appears that something is wrong at the Thunderbird end.

Any suggestions as to what the problem might be, or what I should be checking for? I recorded an imap.log, but I cannot understand what it says.


Harry

Harry

[tanstaafl]

Check your smtp server settings (they are separate from your account settings).

Are you using a multiple identity or is a folder selected in the second providers account when this happens? A multiple is a clone of the accounts settings, that you then typically edit just the From: address.

[genesch]

I'm having the same issue. I think the operative word here is NOTHING has changed from last week, but all of a sudden Thunderbird can't email anything unless I delete the Reply-To Address: in the Account Settings. Keep in mind there has been a Thunderbird update in the last couple of days. The combination of the two facts tells me that Thunderbird changed or hosed something. So, the question is how do you fix it so the Reply-To is what you want and when will Mozilla fix this issue?

[tanstaafl]

Genesch:

Normally you can delete a reply-to address before sending, if its automatically added. Have you tried that? The reason I suggest that is perhaps that header is not the cause, but a symptom of something else that is causing the problem.

I can't find a bug report about that problem. You can submit one at https://bugzilla.mozilla.org/home . Its NOT a support channel.

You can increase your chances of somebody taking the bug report seriously if you install the prior version of Thunderbird in a separate directory using custom setup (don't uninstall the current release) and verify the problem doesn't occur with it, using the same profile. See http://kb.mozillazine.org/Go_back_to_an ... hunderbird if you want to do that. Normally there is no reply-to address in the account settings (it is blank).

Realistically , if a developer can't reproduce the problem it tends to get written off as due to a user error unless there are a number of reports about it for the same version, or you can show through a description of what troubleshooting steps you took that its worth looking into. I'm not saying there isn't a real bug, I'm just saying the bug reporting system is flooded with unconfirmed bug reports, and you need to be pro-active to get somebody to pay attention to your bug report..

I suggest you move any downloaded mail to a safe location in "Local Folders", delete the broken account, exit and restart Thunderbird. Add the account (using the new account wizard, which should run automatically if you have no POP or IMAP accounts) and see if the problem occurs. If it doesn't , move your downloaded mail from Local Folders to that account.

I searched SUMO (the official support forum) and couldn't find any recent posts about mailbox unavailable errors. You could use the profile manager to create a new profile, with just one account. See if it has the same problem. If it doesn't, then migrate your address books and downloaded mail to it. While its possible you ran into a bug in Thunderbird, the odds are its a problem with the profile (despite your statement you didn't change anything).

http://kb.mozillazine.org/Profile_Manager
http://kb.mozillazine.org/Transferring_ ... hunderbird

[bex1210]

Check your smtp server settings (they are separate from your account settings).

Are you using a multiple identity or is a folder selected in the second providers account when this happens? A multiple is a clone of the accounts settings, that you then typically edit just the From: address.

Check your smtp server settings

Are you asking about my Outgoing Server (SMTP) Settings, or the Server Settings for a specific account?

Are you using a multiple identity or is a folder selected in the second providers account when this happens?

Not clear what you mean. When I send to or from an email address in provider2, I select the specific user name. And when I am replying to an Email sent to an address in provider2, I just select Reply in Thunderbird.

And as I said in my initial post, I have not made any setting changes since everything was working fine. And unlike the other person who noted he has a similar problem, I have NOT updated Thunderbird.


Harry

[tanstaafl]

I was asking about the smtp server settings, NOT the account settings. The account settings do specify which smtp server entry to use.

See http://kb.mozillazine.org/Multiple_iden ... il_account for an explanation of what multiple identities are.
"Thunderbird will let you select any accounts From: address in the From: drop down list. However, in most versions that identity is not actually used unless its either the current accounts identity, a multiple identity defined for the current account or you set mailnews.reply_to_self_check_all_ident to true."

Do you have more than one account ("Local Folders" doesn't count as a real account)? If so does this problem occur with all of them? Its useful to have a second account such as Gmail IMAP to help troubleshoot who/what is at fault, and as a emergency backup. http://kb.mozillazine.org/Gmail

[bex1210]

I was asking about the smtp server settings, NOT the account settings. The account settings do specify which smtp server entry to use.

See http://kb.mozillazine.org/Multiple_iden ... il_account for an explanation of what multiple identities are.
"Thunderbird will let you select any accounts From: address in the From: drop down list. However, in most versions that identity is not actually used unless its either the current accounts identity, a multiple identity defined for the current account or you set mailnews.reply_to_self_check_all_ident to true."

On my 'Outgoing Server (SMTP) Settings' screen, there are 7 servers listed: one for provider1, 5 for provider2, and one for att. ATT is the Default, and is used for all 5 accounts at provider2 and the one account at att. Account1 uses the provider1 server.

Only Account1 has multiple identities (two). For it, mailnews.reply_to_self_check_all_ident is set to false.

Do you have more than one account ("Local Folders" doesn't count as a real account)? If so does this problem occur with all of them? Its useful to have a second account such as Gmail IMAP to help troubleshoot who/what is at fault, and as a emergency backup. http://kb.mozillazine.org/Gmail

I have seven accounts (as listed on the Account Settings screen). : 1 at provider1, 5 at provider2, and 1 at att. The problem occurs when sending to or from any of the provider 2 accounts, or replying to or from any of the provider2 accounts. And as I said in my initial post, the problem only started a week or so ago. If I go to provider2's webmail page to send from or reply to, etc., the problem does NOT exist.

To my knowledge, NO settings had been changed that might have caused this problem.


Harry

[tanstaafl]

Webmail does not use a SMTP server, it calls a shared library that uses the SMTP protocol instead. Big difference. Being able to send mail via webmail mainly means your login credentials are valid, the host isn't being blacklisted by the recipient as a spammer, and the DNS server they are using is working fine. It sounds like the 5 SMTP server entries for provider 2 might be wrong.

Please don't get hung up on the fact you didn't change the settings, focus on whether the settings are right instead. Can you use the existing SMTP server for provider 1 or 3 with those accounts instead? If you can that provides a temporary workaround, and would appear to confirm that the problem is with the 5 SMTP server entries for provider 2.

There have been a few cases where a upgrade to Thunderbird changed settings (even though it shouldn't have). Since you got back a SMTP error from the server that seems to rules out a server specific firewall problem. If it only effects one email provider's SMTP server that seems to rule out your anti-virus scanner or security suite being the culprit. It's possible that email provider 2 might have quietly changed the settings they require. I've seen that occur with large ISPs.

[sfhowes]

There is a recent post that suggests you have to 'register' non-Yahoo (Yahoo, Sky, AT&T, Verizon, Rogers, AOL etc.) accounts if they are used as reply-to addresses:

https://support.mozilla.org/en-US/questions/1260312

[bex1210]

There is a recent post that suggests you have to 'register' non-Yahoo (Yahoo, Sky, AT&T, Verizon, Rogers, AOL etc.) accounts if they are used as reply-to addresses:

https://support.mozilla.org/en-US/questions/1260312

This seems to mainly work, and for that I am grateful. If it had not been for your very explicit instructions (though you didn't say they would not work with a Yahoo 'Basic' Email setup) I never would have been able to set this up. Some of the screens seem non-intuitive to me.

But I am really confused on some things:
1. What exactly is the definition of a 'Send-only' account? What can I do with it, and what are the restrictions, compared to a 'normal' Email account? The answer I get from the Yahoo help page is of no help.
2. Should I be able to send from one 'send-only' account to a 2nd 'send-only' account?
3. If the answer to #2 is Yes, should it appear in Thunderbird in the Sent folder from the sending address AND in the Inbox of the receiving address?
4. Would your answers to #2 and #3 differ if either the sending address or the receiving address was listed as 'non-verified'?


Harry

[tanstaafl]

I think the relevant terminology is send-only address, not send-only account.

Some email providers will not let you use a additional/different From: address with their SMTP server unless you register it using webmail. In some cases they return an error message if you don't do that (Yahoo). In other cases they ignore the specified From: address and silently replace it with the accounts From: address (Gmail).

https://help.yahoo.com/kb/SLN26524.html
https://support.google.com/mail/answer/22370?hl=en

[bex1210]

Webmail does not use a SMTP server, it calls a shared library that uses the SMTP protocol instead. Big difference. Being able to send mail via webmail mainly means your login credentials are valid, the host isn't being blacklisted by the recipient as a spammer, and the DNS server they are using is working fine. It sounds like the 5 SMTP server entries for provider 2 might be wrong.

Please don't get hung up on the fact you didn't change the settings, focus on whether the settings are right instead. Can you use the existing SMTP server for provider 1 or 3 with those accounts instead? If you can that provides a temporary workaround, and would appear to confirm that the problem is with the 5 SMTP server entries for provider 2.

There have been a few cases where a upgrade to Thunderbird changed settings (even though it shouldn't have). Since you got back a SMTP error from the server that seems to rules out a server specific firewall problem. If it only effects one email provider's SMTP server that seems to rule out your anti-virus scanner or security suite being the culprit. It's possible that email provider 2 might have quietly changed the settings they require. I've seen that occur with large ISPs.

Let me answer this one now, even though I already sent a note to sfhowes, and have seen your latest post.

I tried using the existing SMTP server for provider 1 or 3 with some of the provider 2 accounts. Same problem.

I then did an online chat with a technician from provider 2. As it turns out, he uses Thunderbird for his email, so he sent me the server settings that he uses. They were different from mine. I changed my settings to match what he sent me. That did not help. Same problem. (I then reverted back to my previous settings)

Once he learned that I was not using provider 2 as my outgoing server (since I had switched to AT&T, as I noted earlier), he said using their accounts would not work. He could not explain why everything worked for 9 months and then stopped. He did not know of any changes made at their end. And since I can still use provider 2's webmail, that means that my login credentials are still valid.

So I added a couple of additional provider 3 subaccounts, assuming I would just delete my provider 2 accounts from Thunderbird. But then I opened the link that sfhowes provided, and found that setting up the provider 2 accounts in ATT/Yahoo as 'send-only' seemed to work--at least most of the time.

Those issues prompted me to reply to his post, which you responded to. You answered question #1, but I still would like an answer to question #2 thru #4. As asked in #3, I find that I sometimes get an error message, and that the email does NOT appear in the Sent folder of the sending address.

So far I have not changed provider #1 from a 'non-verified' account. I have never had a problem sending or receiving with it, as long as I am not sending to or receiving from a provider #2 account.

Harry

[tanstaafl]

2. Should I be able to send from one 'send-only' account to a 2nd 'send-only' account?

You don't appear to be using a send-only account. You appear to be using a send-only address. The difference is important. A send-only account implies you do not have any POP or IMAP account for that address, you merely have a SMTP server defined for it, which you are using with a POP/IMAP account with a different default email address.

Using that definition you can't send from any account (including a send-only account) to a send-only account. You could send to a mailbox used by the corresponding webmail though.

4. Would your answers to #2 and #3 differ if either the sending address or the receiving address was listed as 'non-verified'?

I don't know what is implied by non-verified. That sounds like email provider specific terminology.

[bex1210]

You don't appear to be using a send-only account. You appear to be using a send-only address.

You are correct. I keep using the wrong term! So sorry.

All I can find about a send-only address on the Yahoo Help section is this:
https://help.yahoo.com/kb/sln26524.html

"Yahoo Mail lets you send messages that appear to be from another one of your email addresses without having to leave your Yahoo Mail account. After a send-only account is added, you can select that address in the "From" field while you're composing or replying to emails."

With my limited knowledge, I can read that one of two ways (assuming Yahoo did not mean to say send-only account):
1. The email is sent from address1 to address2 all within Yahoo: i.e., without going out on the web to look for address2;
or
2. It is being used to spoof the recipient, who thinks the Email is from address2, but it is really from address1.

Do you have any idea what the Yahoo statement really means?

Harry

[bex1210]

UPDATE:

I did some extensive searching, and I found that AT&T (my ISP) has a forum, with a section devoted to AT&T Internet Email. As I noted above, AT&T uses a rebranded Yahoo mail.

So I left a post asking for clarification on their send-only address, and how the feature is supposed to work. I will post here any information I receive.

Harry