If you are using an imap mail account, it is possible the server has automatic policy to delete emails after x days that were selected as trash and not wanted. This is quite common on servers and they differ in times kept on server. eg: gmail auto empties after 30 days.

If imap check settings: Right click on imap mail account name folder in Folder Pane and select 'Settings' Select 'Server Settings' Under 'Message storage' section Uncheck 'Empty Deleted folder on exit'

Select 'Synchronisation & Storage' In the 'Disc Space' section Select 'synchronise all messages locally regardless of age' Select 'Don't delete any messages'

If pop then check settings: Right click on pop mail account name folder in Folder Pane and select 'Settings' Select 'Server Settings' Under 'Message storage' section Uncheck 'Empty Deleted folder on exit'

Select 'Disc Space' Select 'Don't delete messages'

Click on 'OK'

Never keep emails you want in the 'Trash' / 'Deleted' folder, it is really a folder to be used to emails you definately do not want to keep. But using a 'Deleted' folder is helpful if you delete an email in error and need to retrieve.

Thank you for your message. However, all the settings that you told me to check and change if needed had already been done, i.e. all your required settings were the existing settings in each case.

My email account is a gmail account - and hence an imap account. There remain 30 days worth of deleted emails in my Thunderbird 'Deleted' box at any one time. Each 24 hours that passes results in another days worth of emails being disappearing from the 'Deleted' box. Clearly, Thunderbird is still synchronising its 'Deleted' box with my deleted box on the gmail server. Can you have another think as to how to stop it doing this?

If there is no way that this can be done, then I must still say that this is not what I want Thunderbird to do. As I have said, all new emails arriving in my 'Inbox' are read and dealt with. A lot of them - important ones - will be copied into various folders in my personal filing system, outside of Thunderbird and the original moved from the 'Inbox' to the 'Deleted' box. For these to disappear after 30 days is not a problem, as there is a backed-up copy elsewhere on my system. Apparently unimportant ones are just moved to the 'Deleted' box, without being copied elsewhere. It is a tiny number of these that are the problem. For example, every now and then, there is one of these that I want to access again, after deleting it maybe 60 days previously. Experience shows me that I will never need to access a deleted email more than 180 days after deletion.

That is how I operated my now defunct Windows Live Mail account. Windows Live Mail does not synchronise with the gmail server in this way. Anything that goes into the 'Deleted' box in Windows Live Mail stays there until it is actually deleted by the user. I used to leave emails in this 'Deleted' box for 180 days before deleting them myself.

How can I do this with Thunderbird? Could I create another box - labelled, perhaps, 'Pending' - and, if so, could this box be arranged to retain all emails until I chose to delete them?

I thank you for your help so far and I look forward to your response.

Wil. Tongue.

re :My email account is a gmail account - and hence an imap account. There remain 30 days worth of deleted emails in my Thunderbird 'Deleted' box at any one time. Each 24 hours that passes results in another days worth of emails being disappearing from the 'Deleted' box. Clearly, Thunderbird is still synchronising its 'Deleted' box with my deleted box on the gmail server.

This fully explains your 'deleted' email problem.

All imap account folders synchronise with server. Imap account folders can only show what is on the server, imap account folders are not a separate copy because folders synchronise; it is more like a virtual view of the server. That is how all imap accounts work regardless of email client. Thunderbird (nor any email client) has any say in the matter. If you put email into gmail imap 'Trash' folder then you are doing this on the server. Then, if you have not personally set a setting to empty the TRash on exit from Thunderbird, gmail will delete email after 30 days in the trash because gmail assumes you do not want them otherwise they would not be in the Trash. This is a gmail policy which they operate to clear up space on server and nothing to do with Thunderbird.

re :A lot of them - important ones - will be copied into various folders in my personal filing system, outside of Thunderbird

I presume you are keeping them as .eml files, so you can use Thunderbird to read them. That's a good way of keeping a copy and keeping your quota down on the server.

re :Could I create another box - labelled, perhaps, 'Pending' - and, if so, could this box be arranged to retain all emails until I chose to delete them? Correct - this is your best way forward. You can create any folder/label you like in imap gmail account for organising/storing emails, make sure you have subscribed to see it as that folder will also get created on server, but you would have to 'move' the email into that 'Pending' folder. So when you select to 'move' emails from 'Inbox' to 'Pending' this is occuring on the server and you will be able to see it either via Thunderbird imap account or via webmail. When you select emails in that 'Pending' folder and click on 'Delete' then those emails would still be moved to the gmail 'Trash' folder and auto emptied after 30 days.

re :Windows Live Mail does not synchronise with the gmail server in this way. Anything that goes into the 'Deleted' box in Windows Live Mail stays there until it is actually deleted by the user. I used to leave emails in this 'Deleted' box for 180 days before deleting them myself. Sounds like this was a POP account. You have full control over deleting in a pop account. Pop accounts only access and download from Inbox. They do not have access to any other server folder and do not synchronise with server. Pop folders are completely independent of the server and only on your computer, which is not the case with imap accounts. However, because you would not be able to put emails into the server gmail Trash folder, it would necessitate logging onto the server via webmail in order to manually delete a load of emails from the 'All Mail' folder every once ina while to free up quota. Also pop accounts tend to have a lower server quota than imap.

Thank you very much for your continued help here. Let me deal with points arising from your response :-

1 No, it was not a POP account on Windows Live Mail it was the same gmail account as now and hence IMAP. However, when I look at my Windows Live Mail software (it is still on my computer until I sort out everything with Thunderbird), I can see that my 'Deleted Items' folder was, in fact, one that I had created within Windows Live Mail. Hence everything that I put in there stayed in there until I personally deleted it, after 180 days.

2 Yes, emails that have been copied into my personal filing system over the years (via Outlook Express and later Windows Live Mail) - and there are more than a thousand of them now - get copied automatically with the .eml file suffix. One of the reasons why I chose Thunderbird, when I decided that Windows Live Mail had no future as Microsoft were not supporting it anymore, was because it would display all my old .eml files and allow me to print them etc. The new Microsoft Mail program, that was being pushed with Windows 10, did not seem to be able to do this, or at least I could not find out how to do it. This was no use to me, as I clearly needed to be able to view my vast number of existing .eml files.

So, yes, I need to be able to create a new folder - peculiar to me - called perhaps 'Pending'. I would then move everything into 'Pending' and not 'Deleted' as I do at the moment. I would then self-delete emails from 'Pending' every six months, as I do now in Windows Live Mail. But just one point, Thunderbird shows another existing folder called 'Junk'. Could this be used by me as a sort of Pending folder - what I mean is, does the 'Junk' folder get auto emptied by gmail every 30 days?

Anyway, assuming that I have to set up my new folder called 'Pending', could you please explain how I do it? And, finally, what do you mean when you say 'make sure you have subscribed to see it'? Subscribed to what? I actually have no idea what goes on on the server of an email provider, as I never use webmail - that is why I have an email client like Thunderbird.

I thank you profusely and look forward to hearing from you in due course.

I don’t use gmail (or IMAP) but, gmail help pages say you can use IMAP or POP so use whichever you prefer. I would expect that if you use IMAP, things done on the server are expected to be replicated in the client.

Thunderbird should allow you to create folders. I do it all the time. (Like I said I only use POP but I don't think using IMAP would prevent that.) Make sure you create them under Local Folders if you want these to be separate from what's being done one the server.

I would NOT use the junk folder for this purpose. That is intended for managing emails that Thunderbird thinks are spam/junk (once you have trained it and set it to move junk messages here.) You don't want to be wading through spam to find useful emails. (Also I don’t know how you have yours configured, but I have Thunderbird set to automatically delete junk emails > 14 days old – probably not what you want for your "pending" folder.)

How to create a folder in an imap mail account:

• Right click on the imap gmail mail account name folder in Folder Pane and select 'New Folder' from the drop down list.
• Give folder a name eg: Pending
• click on 'Create Folder'.

How to subscribe to see folders that are on the gmail server:

• Right click on the imap gmail mail account name folder in Folder Pane and select 'Subscribe'
• Click on 'Refresh'
• Select folder name
• click on 'Subscribe' button
• click on 'OK'

Good info on Gmail:

• https://support.mozilla.org/en-US/kb/thunderbird-and-gmail

How to select to have full copies downloaded:

• https://support.mozilla.org/en-US/kb/imap-synchronization#w_configuring-synchronization-and-disk-space-usage

Gmail webmail, default folders and selecting folders to 'Show in imap' info: Gmail tend to use specific names for certain non deleteable default server folders. eg: Junk is likely to be an added folder as gmail use the 'Spam' folder. If you logon to gmail webmail account: Click on the gear wheel icon and select 'Settings' then select 'Labels' column header you will see something similar to the third image below. 'System Labels' are the default folders, which you can choose to 'Show in Imap' or not by unchecking the checkbox. 'Categories' is something you can only use in the webmail account. You cannot use these as imap folders. 'Labels' This section shows all the folders (gmail call them labels) you have created. You can select the checkbox to 'Show in Imap'. This means, in Thunderbird, you can subscribe to see these folders. As you can see I created a 'Junk' label, just to show you the difference between the server default 'Spam' folder and the 'Junk' folder I created. Note: some gmail server use the 'Trash' label, but others use the 'Bin' label. (I'm in the UK and I see 'Bin'). I would strongly advise that you make sure you are using the default server folders for 'Drafts', 'Spam', 'Sent Mail' and 'Trash'/'Bin'. Why? Well, if you cannot see 'Spam' folder in Thunderbird and it is not available for you to 'Subscribe' to see, is the 'Spam' 'System Label' selected to 'Show in Imap' ? Gmail maybe automatically putting spam emails into the server 'Spam' folder and you may miss them if you have not subscribed to see that 'Spam' folder.

How frequently does gmail automatically empty the 'Spam' folder? If you just leave the messages in 'Spam', they will be permanently deleted after about 30 days. They will never go to Trash. This gives you time to check emails in Spam just in case some are not spam emails and you want them.

Thank you both very much for your help. I have now created a 'Pending' folder as a 'Local Folder' and I have started to move my Inbox messages into this folder (after reading them and dealing with them as required of course) as opposed to moving them to the 'Deleted ' folder, where they were being permanently deleted by Gmail after 30 days. I understand that I have control over the 'Pending' folder and that I can leave emails in there for as long as a wish, before eventually deleting them myself when I want to. I have also moved the entire contents of the 'Deleted' folder into the new 'Pending' folder, so as to prevent any more premature email losses.

I have another issue with the order of incoming emails as they appear in my Inbox but this is a totally different problem and so I will start a new thread for this.

I thank you again.