How to Set an Out of Office Reply in the Gmail App
Gmail on the web; app differences noted · Last checked · Suggest an edit
https://instructions.wiki/gmail/set-up-out-of-office-in-gmail-on-a-phone
You are leaving without a laptop and the automatic reply still needs setting. The out of office responder is not on the compose screen or the message list, it sits inside the per-account settings in the app, which is why it looks missing.
Open the account settings
Open the Gmail app and tap the three-line menu at the top left. Scroll to the bottom of that panel and tap Settings. Tap the address you want the reply to come from. Each account is configured separately, so a reply set on a personal address does nothing for a work one.
Open the responder
On Android or iPhone, tap Vacation responder. Tap the switch at the top to turn it on.
Set the dates
Tap First day and pick the date replies should start. Tap Last day if the reply should stop on its own, otherwise leave it off and it keeps running until you turn it off by hand.
Write the subject and message
Fill in Subject and the message body. Say when you are back and who to contact meanwhile. Turn on Send to my Contacts only if replies should go to known senders rather than to every stranger who writes in.
Save it
Tap Done on Android or Save on iPhone. While the responder is active, a banner sits at the top of the inbox showing the subject, with End now to switch it off without going back into settings. The setting syncs, so the same responder shows on the web.
How often it replies. The same sender gets the reply at most once every four days, and editing the message resets that so they receive the new version. Nothing is sent to mailing lists or to mail that lands in Spam, which keeps the responder from confirming the address to junk senders.
Work accounts may differ. On a Google Workspace account the administrator can restrict or preset this, and an extra option appears to reply only to people inside the organization. If the setting is greyed out, it is being controlled centrally.
Sources. Send an automatic reply when you're out of office - Android - Gmail Help, Send an automatic reply when you're out of office - iPhone & iPad - Gmail Help.