How does ColdMerge send my mail?

ColdMerge sends through your connected Gmail or Google Workspace account. Your address appears in the From field, the message uses that mailbox’s Google quota, and replies arrive in its inbox.

What sent means

Sent means Gmail accepted the message and placed it in your Sent folder. It does not prove that the recipient’s provider delivered it to an inbox, or that the recipient read it.

ColdMerge does not report a delivery figure because Gmail does not provide one.

When a send fails

An address-related failure gets up to three attempts. The retries wait one minute and then five minutes. After the third failed attempt, that recipient stops for the campaign and the Messages screen shows the reason.

A mailbox-related failure does not use one of those attempts. Gmail quota, temporary rate limits, an administrator block, or a mailbox needing reconnection put the recipient back in the queue.

When ColdMerge cannot confirm a send

A process interruption can leave ColdMerge unsure whether Gmail accepted a message. ColdMerge searches the Sent folder before deciding what to do.

• If the message is found, it is recorded as sent.
• If it is confirmed absent, the recipient returns to the queue.
• If the result remains uncertain, ColdMerge does not send another copy because the first copy may already exist.

The recipient’s row explains the unconfirmed result, and follow-ups stop for that conversation.

Mailbox rotation

When a campaign has several mailboxes, ColdMerge spreads different contacts across them. A contact is assigned to one mailbox when their first message sends. All follow-ups for that campaign stay in the same Gmail thread and use the same mailbox.

If that mailbox becomes unavailable, its follow-ups wait. They do not move to a different sender.

Safeguards that are always on

• Suppression is checked immediately before every send, including previews.
• An unsubscribe, an opt-out you mark, or a permanent bounce stops later sends to that address.
• Verification results do not add addresses to the suppression list.
• Reply detection checks only threads ColdMerge started.

Open and click tracking are optional. See Open and click tracking. The one-click List-Unsubscribe header and the visible unsubscribe footer are optional too, and both start off. See Add an unsubscribe footer or header.

Why there is no automatic warm-up network

ColdMerge does not exchange artificial messages with other mailboxes to imitate engagement. It uses gradual ramp-up based on mailbox age and real sending history instead.