Here’s how to bulk delete emails from your Gmail account to speed up the Apple mail app.
OSX slows down if you have too many emails in your gmail account. So I’m going to show you how to delete mail from your gmail account. (They will be completely gone so you may want to back them up first.)
In the google mail search bar type in ‘older_than:2y’ This will find out all your emails that are older than 2 years old. If you type in ‘older_than:3y’ it will show you all the emails older than 3 years old and so on.
To select all the emails that you have just found, click the little tick box with the down arrow up the top of the window. You should get a yellow message like the one above. Click on ‘Select all conversations that match this search’
Press the trashcan icon to send all these emails to the trash.
Find and click on the ‘trash’ label in the left column of google mail. (If it is not there you may need to click on ‘More’ to show the Trash.)
Now click on ‘Empty Trash Now’.
You will get a checkbox confirming that you want to delete them. Click OK to proceed. This will permanently delete all the emails.
I deleted all emails older than 2 years old and this reduced the number of messages from 85,000 to 15,000 and dramatically increase the speed of Apple’s OS X mail app.