Who is your email provider for each account ?

You may try reconfiguring them from scratch using the Thunderbird assistant for that, it will validate the information before finalizing the setup.

Thanks Fabian I seem to have solved this problem for the time being by adding TB to the trusted sites of my Anti-Virus/Firewall program and then removing it again. I was concerned that putting it there would reduce the protection on incoming emails. Anyway, even after removing it again, TB seems back to normal so I will see how that goes. Is there anyway to find out when TB was last updated? Thanks

So you have removed Thunderbird from the trusted programs. Welcome to hell is the best I can say to you. Put it back in as trusted or get used to it not working.

Basically you only touch the firewall if something is not working. Changing settings without a cause is usually a recipy for taking the box to someone and paying them to fix it.

Am a bit confused Matt. TB was not originally in the trusted list and was working for years up until 2 days ago. Is it something new that requires it to be in the trusted list? If so, does that also mean that TB becomes a vulnerable point for viruses etc infecting my computer?

I have no idea what anti virus you use, or what firewall prodiuct it infest your computer with.

But lets look at how firewalls used to work. protocols and ports were blocked or allowed at the edge. This is because it really does not matter is your browser is Internet Explore, edge, Firefox, Chrome or Safari, outgoing connections from those programs need to be made on port 80 using HTTP.

Likewise, an email client, regardless of which it is needs to open outgoing connections to internet servers. In these cases they are mail servers and use IMAP, POP and HTTP. commonly on ports 465,587 etc.

Now we get to the anti virus vendors, who seriously have a lot to answer for in selling fear. They decide a firewall that locks down ports and protocols is just not enough to make them look good in marketing material so they all invent an application firewall. What this means is now we start mucking around allowing individual applications to connect to the internet and on what ports. So now they need something else to differentiate their product. So they start allowing applications by version. So you allow Thunderbird this week as V52. next week you get and update and that allow is no longer valid as the version is now 52.4. or 54.9.

In the end, I have no anti virus/security suite firewall. The one that comes with Windows does more than enough in that regard. After data passes through the firewall on my Router/modem I have no anti virus scanning my email. I do not suffer from corruption issues all the time, I do not have random occasions after update when nothing can connect and I do not have a virus. At least not one my anti virus can find.

Holidays21 said

If so, does that also mean that TB becomes a vulnerable point for viruses etc infecting my computer?

No it means the program can run as the developers intended without outside influence to retard it's ability to function. If programs that connect to internet services are not trusted, they simply do not work correctly. Be it Thunderbird, Chrome, or Skype

I agree with Matt completely disabling the antivirus for Thunderbird is not an ideal solution, it needs careful handling of attachments and following best practices even when having email preview on.

It would be useful to know which antivirus and which version of Windows (7,10..) you are using. They may have changed (and tightened) their restrictions which may explain why this worked before and why it doesn't now.

This is a frequent problem with Thunderbird in Windows. I don't use Windows so I can't recommend a specific antivirus to use, but I support at least one customer (in my day work) who uses ESet NOD32 anti-virus. My primary work environment is GNU/Linux.

I lack the time right now to properly check if there are references to this in the knowledgebase, perhaps another volunteer with more Windows experience can help out and suggest an antivirus that can work well with Thunderbird under Windows.

I have had he same problem, but have found the solution to be that the outgoing server settings defaults to the same set up, despite the email address needing to be changed.

For instance Hotmail.com accounts use the same SMTP server, so Thunderbird allocates the same setup details, and just adds the email address, but keeps the same profile name, which includes the original email address, which is why the mail server throws an error.

You need to change the profile name (at the top of the outgoing server setup details) to the account you are using it, for ie "Microsoft Live Hotmail myaccount1", so it is different from another account on the same provider which uses the default "Microsoft Live Hotmail".

You will only find this out looking at the OUTGOING SERVER (SMTP) SETTINGS at the bottom of the account settings menu, there should be a different smtp server entry for EACH outgoing account (mine had one missing), other wise only the first account will be able to use the outgoing SMTP account! This is a bug in Thunderbird that needs to be fixed.

stephenc said

I have had he same problem, but have found the solution to be that the outgoing server settings defaults to the same set up, despite the email address needing to be changed. For instance Hotmail.com accounts use the same SMTP server, so Thunderbird allocates the same setup details, and just adds the email address, but keeps the same profile name, which includes the original email address, which is why the mail server throws an error. You need to change the profile name (at the top of the outgoing server setup details) to the account you are using it, for ie "Microsoft Live Hotmail myaccount1", so it is different from another account on the same provider which uses the default "Microsoft Live Hotmail". You will only find this out looking at the OUTGOING SERVER (SMTP) SETTINGS at the bottom of the account settings menu, there should be a different smtp server entry for EACH outgoing account (mine had one missing), other wise only the first account will be able to use the outgoing SMTP account! This is a bug in Thunderbird that needs to be fixed.

All good, except they are SMTP server names, not profile names. Correct terminology is important, especially when you use a term that is also used elsewhere in the program.

Matt, the mail server "smtp-mail.outlook.com" is llisted under the server name in the settings dialog box for SMTP. That's why I used the "profile name" which is what the setup is saved under for each account. I am sorry if this is the wrong description, but Thunderbird does not give this file a name, it certainly is not "SMTP Server Name".

Well you could use account Description I suppose. That is what the dialog uses as a label for the field. The problem with using profile is it is confusing. That is my only point here.

The label used to name an SMTP server should not be confused with profile which is all the settings and data that is in Thunderbird. See https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data

Unfortunately Thunderbird does use the server name to label the entries in the SMTP server list, But even if we were to ask the user, they would put in their email address, and that would be probably worse,

When you remove an incoming account in Thunderbird the outgoing account remains. So there would be lots of folk with 2 or 3 outgoing server names using their email address. Especially confusing when there are three entries when you look in the SMTP server setting in the incoming account all using the email address as the server name/Label.

The reality is the "description" needs to be a useful descriptive label, so you can select the correct SMTP server in the incoming accounts section of account settings.

Why is this important to me? Because we have folk removing accounts all the time in the futile hope it will fix something, just like they remove and reinstall the software. We even see ISP help desks telling folk to do it, or in a few cases removing the accounts for people using remote sessions. They then turn up here with their original problem unresolved but complicated by the fact the mail they had in the removed account is now gone.

Matt,

the real problem is the location of the SMTP server set-up, 

It is separate to the account details that it supports.

Maybe it should be re-written to be included in the account information for that email account. Then it would specific to the email address, instead of divorced from it, and it could be stored under the account settings folders.

While I agree with you in part, I have come to understand how that is not really practical in a mail client with Thunderbird's feature set. I accept that Microsoft have trained most folk that incoming and outgoing is all one big account, and that reinstalling fixes problems. However the reality of email is different to most peoples expectations. Sending is on a different server, using different protocols and can include different credentials. Just because it is an expected one to one, and most people never go beyond that. There is no requirement for it to be that way and there are many use cases that use multiple sending servers for a single incoming account. It might be as simple as someone setting up gmail to collect their comcast mail. when they reply they will want to see a comcast address, not the gmail one. Thunderbird through it's support of identities can have many SMTP servers configured for a single incoming account. neatly handling the sending of gmail and comcast from one inbox.

Each identity can have it's own SMTP server and the server may have nothing at all to do with the incoming email address at all. Helpful if you are sending mail for our boss as well as yourself, one identity for the boss that sends mail from the bosses account and another that sends mail from your business account. You might also be sending mail as say the union rep, so you have another identity. The boss and the union have forwarded mail to your business account, so you get all the email in the inbox for your business account. For replies however you need the correct outgoing identity.

After years of argument there is now an edit server button beside the entry in the "Identity" part of the incoming account. (The pane above "server Settings". This is provided so the inexperienced can locate the correct SMTP server entry to edit and those who expect a one to one relationship can navigate to where they need to go. Note that each Identity has a similar edit SMTP.