No, you cannot. We recommend that you keep backups before deleting emails which may be necessary later.

Confirming mailbox usage / How to move your email data to another location
https://www.u.tsukuba.ac.jp/en-email-backup/

There are a couple of possible causes.

1. Your mail forwarding is set to send the e-mails to another address, but not retaining any e-mails in the Zengaku system server.
2. You have used up the disk capacity for your e-mail address, therefore cannot save the new mail any more. (If you have received messages such as “maildir delivery failed: Disk quota exceeded”, then it is likely the case.)
   → Please erase your old e-mails from the server by using your e-mailer.

Please see E-mails of Zengaku Computer System.

E-mail clients other than Microsoft Outlook and Apple Mail require registration by a Microsoft 365 administrator.
Sending and receiving e-mails with an unregistered e-mail client may result in errors.
The e-mail clients registered to date are listed below.
Available SMTP, IMAP and POP clients
If you wish to use an e-mail client not listed here, please contact icho-inquiry{at}cc.tsukuba.ac.jp.

If you have not used Microsoft 365 before, you will need to set a password at the following website.
Cloud mail service authentication setting system (on-campus only)
If you are off-campus, you can connect using a VPN setting on your smartphone or other device.

No, you cannot.

Students who enrolled before the 2022 school year, for whom @s email is provided, can continue to use it. It is independent of @u.

We do not recommend setting up e-mail forwarding in Microsoft 365. You will also receive a warning message when you sign in.
These days, some e-mail systems seem to reject forwarded e-mail.　Please set up forwarding at your own responsibility.

No, you cannot. You can read and write e-mails by adding an Exchange account.
Please refer to the E-mail Client Settings site.