Your existing marketing emails deserve a place in your swipe file.

Use an EML file for an individual email. Use MBOX for a group of messages exported from a mailbox. PromoStash parses the sender, recipients, subject, date, available HTML and text, and headers, then adds each message to the same archive as your newly received emails. Imported messages are grouped by sender domain and can be added to collections.

Forwarding as an attachment is useful when you want to preserve the original message structure. In Gmail on a computer, select messages and choose Forward as attachment. Send them to your private PromoStash address; attached EML messages are processed separately. A normal inline forward may retain the forwarding sender or modified formatting, so use EML attachments when original sender details matter.

The current uploader accepts .eml and .mbox files up to 4,000,000 bytes (4 MB). An MBOX batch can contain up to 100 messages. Forwarded attachment processing supports up to 20 attached emails. Split a larger export into smaller batches before uploading; PromoStash is not an unlimited mailbox migration service.

Imports report saved messages, duplicates, failures, and remaining work. Existing messages are deduplicated using available identifiers and content fingerprints. If the request reaches its processing budget, you can retry the same batch; already saved messages are skipped. Modified forwards may count as different messages, so keep original EML files when possible.

Your plan’s email and brand limits still apply to imported messages. General attachments are recorded as metadata, not stored as a complete binary backup. Keep your source files if you need the original attachments or a separate backup of your exported mail.

For future emails, add your PromoStash address as a forwarding address in Gmail, complete its verification step, and create filters for the senders you want to collect. Forward only the selected newsletters or brands instead of your entire mailbox. The setup takes place in Gmail; PromoStash does not request permission to read your account.

Forwarding does not retrieve past messages. Use EML or MBOX for historical references, and filters for future delivery. Our Gmail forwarding guide walks through that distinction. If you are subscribing to a new brand, you can simply use your private capture address instead.