Are you talking about a Pop or IMAP mail account? Did you create the 'TrashMain' folder?

'Trash' in English US versions or 'Deleted' folder in English British versions is the main Trash folder.

If you are using IMAP mail account renaming can be done, but it is a bit techy; see info at link:

• http://kb.mozillazine.org/IMAP_Trash_folder

It is not a good idea to put emails you want to keep for a while in the Trash folder as Trash is for deleted emails which you do not want to keep. The reason emails are sent to Trash upon delete is to offer the opportunity of moving them back to another folder if deleted in error. Trash is not designed to be a storage for emails that you do not want to delete. You would be better off creating a folder called eg: TempHold' for those emails and leave 'Trash' for deleted emails that are not wanted.

IMAP, I did create the TrashMain Folder.

I understand about the whole idea behind the trash folder (and that's the reason why I wanted to change the folder). With my host, my trash folder periodically gets "emptied", I want to keep all my emails forever so I then decided to make another folder called "TrashMain", is there any easy/simple way to do this?

Thanks

No there is not a simple easy way to do this. The protocol synchronises with the server so you need to convince the server software that the trash folder has changed. I am not aware of a single mail provider that allows that.

If you choose to archive to your local computer disk you can set the trash folder for the account to be trash on local folders and it will remove the mail from the server storage and store it locally.

re: I want to keep all my emails forever

Your provider periodically empties the TRash, which is designed to hold emails that you want to delete/remove/kill.

You are selecting 'Delete' to put items in the Trash, but want to 'delete' items to another 'TrashMain' folder...because you want to keep all emails!

If you want to keep all your emails, why are you choosing to delete them?

Instead, choose to 'Move To' or drag and drop emails into any folder you create either in the IMAP mail account or in Local Folders (see Matts comment) but do not delete something you do not want to delete. Then it will never go to the Trash folder and so will do exactly want you want.

This isn't that complicated. I don't want hundreds of emails to stay in my inbox but I also don't want my emails to be deleted, so, I made a folder called "TrashMain" which will act as the trash folder but won't delete my emails after X amount of days. All that I want to do in Thunderbird is make it were when I delete an email, it puts the email in the "TrashMain" folder and not the "Trash"

Tools menu > account settings >server settings and change the local action to whatever folder you like. Your IMAP server will take no notice. Nor will your phone or other devices