Current situation: You would need to set up each email address as it's own separate mail account in order for that additional identity to use a complete set of it's own folders.

Using Multiple Identities is useful for specific situations - see link - but otherwise it is advised to use a separate account for each email address. https://support.mozilla.org/en-US/kb/using-identities

I do not know the reason why you need to use several identities for one mail account, it may be entirely valid, but I have come across people in the past who used it not realising they could create separate accounts.

Otherwise you could put in a request for an enhancement via Bugzilla, but it is not a guarrantee it will be done. https://bugzilla.mozilla.org/home

My mail provider Posteo offers mail aliases and I want to keep my aliases strictly separated. However a separate log-in for them is not possible, since they are all under the same account (had to double check this first).

I will file a request then. Thanks!

I've just has a look at posteo info and they do say "An email alias is an additional receiving address for your Posteo account and does not have its own password. ...Emails sent to your alias addresses are automatically delivered to your inbox."

So everything is all coming into the main account Inbox. Are you using a POP account ?

I have an idea which you could try which means you use the 'Local Folders' mail account for the 'alias' emails and then when you delete, it should use the 'Local Folders' Trash, so keeping all emails separate.

Set up a 'Message Filter' and It will operate on the new Incoming mail.

• Menu app icon > Tools > Message Filters
• click on 'New'
• Give a suitable name
• Select 'Manually Run'
• Select 'Getting new mail'
• Select 'Filter before Junk Classification'
• Select 'Match all of following' (if there is only one alias)
• select 'TO or Cc' and 'contains' and type alias email address
• Perform these actions:
• Select 'Move Message to' and select 'Inbox in Local Folders' mail account.
• click on OK

Select checkbox to enable the filter and always have that filter at the top of the list. Click on 'Filter Log' to open window and select the checkbox 'Enable the filter log' and click on Close.

If you want to see if it works on the eg: 'Inbox' you can do a manual run. Run selected filter on : choose 'Inbox on mail account' Select the filter to highlight. click on 'Run Now'.

Do emails get moved from Inbox on mail account to Inbox on Local Folders mail account? If you reselect the 'Filter Log' does it correctly show what is moved?

This method should allow you to keep the 'alias' as a separate set of folders and therefore use a separate 'Trash'. You do not have to set up as a separate account and you can keep the current identities format - but the auto filter on new incoming mail may offer you a way around it

If I understand correctly, your presented solution only works for POP since it moves all messages to the local inbox. But since I check mails using several devices (and thus IMAP) I'm afraid this does not work for me.

Also I'm not sure where trash will be moved using this solution. So far I am already using filters to move mails addressed to my alias to a (remote) sub folder.

Maybe someone else can profit from this idea and report back on us :)

Thank you!

re :But since I check mails using several devices (and thus IMAP) I'm afraid this does not work for me.

As discovered all the aliases use the same account folders, this is set by Posteo. This means there is only one Trash folder available on the server.

The only other option which I mentioned would move emails off the server into Local Folders. It does not sound the best solution for imap account.

As this is imap, you can only create a folder and perhaps call it 'Temp'. Then instead of deleting those alias emails, move them into the 'Temp' folder. You could use a tag called 'Del' When you want to delete - just set the 'Del' tag. Then create a Message Filter to run 'Periodically every 10 minutes' TO contains alias email address Tags contain Del Action: Move Message to and select Temp folder on account

Well this would be a workaround indeed. Or I could have a filter move alias messages from Trash to a separate folder. Then I don't have to fiddle around with tags.

Regarding separate folders: Posteo allows you to create folders as well. So as of now I have sub folders for Inbox, Sent and Drafts for the alias and they work and are marked as such in Thunderbird. So I think the folder itself is not the problem, just the assigning it as trash