Can't see 'Add to calendar' link in Gmail
When you're reading an email with calendar-related keywords, an "Add to calendar" link should appear in the right column.
Google Calendar is pretty good at recognizing keywords that trigger the link, but it's not perfect. For example, with short messages, there may not be enough calendar-related keywords to trigger the link. We're working to improve keyword recognition for the "Add to calendar" feature, and we appreciate your patience.
Another thing to keep in mind is that Calendar features are currently only available to users whose Gmail language settings are set to "US English." To learn how to change your language settings, please visit In which languages is Gmail available?