This issue is also affecting enterprise customers of Google who are GSuite. Users are not able to attach or access files and also save draft emails or send emails. Google Drive users are unable to share, upload or download files.
As per DownDetector, Gmail services have been affected in parts of Japan, Australia, Thailand, US and Europe. The outage has been there for quite some now with users reporting it as early as 2AM in the night. Google is yet to release an official statement on the same.
Back in April this year, users reported problems accessing Gmai. Google had confirmed the outage and worked on issues. The problem was mostly restricted to sending emails and it took more than the usual time to get emails across. Other Google services were working fine back then.