Add to calendar from Gmail
to: – Search for messages sent to a specific address.
from: – Search for messages sent from a specific address
subject: – Search the subject field.
label: – Search within a specific label.
has:attachment – Search only for messages that have attachments
is:chat – Search only chats.
in:anywhere – Also search for messages in the spam and trash. By default, Gmail’s search ignores messages in the spam and trash.