Gmail has some limitation of receiving and sending file sizes, if you exceed this limit your Gmail account will be temporarily blocked for 24 hours. Typically Gmail file storage limit is 15GB and send the file limit up to 25MB, if you try to send this file size your account will be blocked. But some more reason also Gmail team will be blocked your account, you must know what are the reasons and avoid your account blocked.
Send Bulk Message
Gmail will not allow sending the bulk message; some people send the promotional mail by using their Gmail account. If the Google found your Gmail account uses any promotional purpose they will blocked your account immediately.
Send or Receiving large files
If you try to send or receive large size of files through IMAP or POP in very short time, your Gmail account will be blocked because Gmail allowed sending or receiving the file size up to 25 MB.
File Sharing and multiple instances
Some people using their Gmail account for Files sharing or file storage by using third-party software. Google will not allow this facility for security reasons, also if you try to access multiple instance to open your account google consider as spam access, so they will possible to block your account.
Related: How to delete or block unwanted email in Gmail
Browser related issues
Many people using various browsers with access the Gmail account some browser is not secured so try to use famous browser such as Google chrome or Mozilla Firefox. If you browser crashed and continually try to login your Gmail account google consider as abnormal access and locked your account immediately. You can also solve the browser related issues by clear the browser cache frequently.
If you would like to avoid your Gmail account temporarily blocked, you must always consider to the above points for securable account access.
Related: How to Send Schedule Mail from Gmail