If a Gmail mail merge stops partway through a recipient list, first determine which messages were sent. Repeating the whole campaign can produce duplicates for people who already received a personalized copy.
Read the failure and check sending capacity
Record the error text, sending account, approximate time, and campaign size. Google’s current mail-merge guide describes a maximum of 1,500 recipients in the To line and a daily mail-merge capacity within the account’s overall sending limit. Ordinary mail and copy recipients can also affect available capacity.
Do not treat a quoted maximum as your guaranteed remaining allowance. Earlier messages and the account’s applicable restrictions matter. Repeated attempts do not reset a quota; wait for the documented reset or follow official support guidance.
Check recipients and merge-field errors
Review invalid addresses, missing field values, and the selected spreadsheet mapping. A missing name can cause a merge error even when the address itself is valid. Correct the source data or use an appropriate default where the feature offers one.
If Gmail cannot read a linked spreadsheet, verify the first tab and text-only contact data. A values-only test copy can isolate hidden formatting while preserving the complete original. Do not change every row until you understand the failing condition.
Resume from verified results
Compare the intended list with Sent, the campaign’s confirmation, and any rejection information. Identify addresses that definitely did not receive an attempted send separately from addresses with an uncertain outcome. Keep unsubscribed recipients excluded.
Prepare a small, authorized continuation for the genuinely outstanding addresses rather than replaying the original list. Review Cc and Bcc behavior, since a copy address can receive one message for every recipient and consume additional capacity. If the result remains ambiguous, investigate the specific send before trying again. A clean recipient ledger is safer than using the absence of a reply as evidence that a message was never sent.
Browse Gmail & Google Account help
References
Reviewed against the linked official product guidance on November 3, 2026. Features, limits, screen labels, and access can vary by account, platform, region, and organization policy.