If you need to copy or transfer all your SSIS emails to a different GMail account, there is an easy way to do it with POP3 access and GMail's "POP Mail Fetcher" feature.
First, login to your old account and go to Settings -> Forwarding and POP/IMAP. In the POP Download section choose to Enable POP for all mail.
There is an additional option for what to do when the email is copied over: Keep email in the Inbox, Mark as read, Archive, or Delete it.
We recommend the option "Archive SSIS copy", but this choice is up to you. Be careful with the option to Delete!
Select "Turn on"
Now it's time to import all of those messages into your new email account. Log out of your old account and then log in to your new Gmail account.
This time go to Settings -> Accounts. In the Check mail from other accounts (using POP3) section, click on Add a POP3 mail account you own.
First enter your old email address:
Second step is to configure the details of the original account:
Now it's just a matter of waiting. Gmail will use the POP access you set up on your old account to download every single message in your old account to your new one. When it's done, all your old emails will be available and searchable in your new email address.