Integration · Backblaze B2
Back up email to Backblaze B2 — automatically.
Forward any email to your private InboxBucket address and the original .eml is written to your own B2 bucket over the S3 API — low-cost object storage from a company built on backup.
Free plan available · No credit card required
- From:
- Acme Billing <[email protected]>
- To:
- [email protected]
- Subject:
- Invoice #4471 — June services
- Files:
- invoice-4471.pdf
s3://your-bucket/inboxbucket/2026/07/0713__invoice-4471__acme-billing.eml
✓ stored · 84 KB · original MIME
Why back up to B2
Low-cost storage, from a backup company.
Backup is their whole business
Backblaze built one of the best-known cloud backup products; B2 is that same durable storage, exposed as an S3-compatible bucket you control. Fitting place for an email archive.
Among the lowest cost
B2's storage price is a fraction of the big clouds, so keeping years of mail — one small .eml per message — costs very little.
Free egress through Cloudflare
B2 gives generous free egress each month, and downloads served through Cloudflare are free — so restoring your archive doesn't come with a surprise bandwidth bill.
How it works
Point it at your bucket, then forward.
Add your B2 bucket
Give InboxBucket your B2 endpoint, region, bucket, and an application key's ID and secret (details on the right).
Get your address
You receive a private inbound address that only receives mail:
[email protected]Forward anything
Forward one message by hand or set an auto-forward rule; seconds later the original .eml is an object in B2.
What you'll need to connect
- Endpoint
- https://s3.<region>.backblazeb2.com
- Region
- the middle segment of your endpoint, e.g. us-west-004
- Access key + secret
- a B2 application key (keyID + applicationKey) — not the master key
- Bucket
- your backup bucket name
Everything comes from your Backblaze console. Pick Backblaze B2 when connecting storage in InboxBucket — it's the same connector as Amazon S3, preset for your B2 endpoint and application key.
The access we ask for
A write-only key, scoped to one bucket.
B2 lets you create an application key set to Write Only and restricted to your backup bucket — so InboxBucket can add objects but never read or delete them. Two B2 quirks worth knowing: the account's master key won't work with the S3 API, so make a dedicated key; and a bucket-restricted key needs the "list all bucket names" capability, or S3 tools reject it.
We're the pipe, not the vault. Mail passes through us only on its way to B2; what we keep is the metadata behind your dashboard — sender, subject, date, status — never the messages. Revoke the key anytime in the Backblaze console, and every .eml already written stays in your bucket.
- A true write-only key — can't read or delete
- Restricted to one bucket — the rest of B2 stays untouched
- Revoke the key anytime — your .eml objects remain
The details
Built like a backup should be.
The message itself, not a copy
Each email is written as a .eml object — the exact RFC 822 bytes, headers and attachments included — openable in any mail client or a text editor, with no conversion.
Attachments arrive whole
Large files upload via S3 multipart, so a 40 MB signed contract lands intact in your bucket, past any single-request size cap.
One object per message
Double-forwards and server retries are deduplicated on Message-ID, so a message is never written to B2 twice.
You choose who's archived
A per-sender allowlist keeps a scraped address from filling your bucket with spam — only mail from senders you've approved is written.
Retries you can see
A failed write queues and retries with visible status in your dashboard, and tells you plainly if the B2 application key needs rotating.
Cheap to keep for years
B2's low storage cost, plus one small .eml per message, makes holding a decade of email genuinely inexpensive.
FAQ
B2 backup, answered.
What endpoint and region do I use for Backblaze B2?
Your B2 S3 endpoint looks like https://s3.<region>.backblazeb2.com — for example https://s3.us-west-004.backblazeb2.com. The region is the middle segment of that endpoint (here, us-west-004); you'll find both on your Buckets page in the Backblaze console. A B2 account lives in a single region.
What credentials does InboxBucket need for B2?
A Backblaze B2 application key: its keyID becomes the Access Key ID and its applicationKey becomes the Secret Access Key. Create a dedicated key — the account's auto-generated master key does not work with the S3-compatible API. Scope the key to Write Only on just your backup bucket (bucket-restricted keys also need the 'list all bucket names' capability, or S3 tools error).
Is Backblaze B2 email backup cheap?
B2 is one of the lowest-cost S3-compatible object stores, and .eml files are small, so archiving years of email costs very little. InboxBucket's own Free plan covers one storage connection; you pay Backblaze separately for storage, which includes a free monthly allowance.
Does restoring my archive from B2 cost egress?
B2 includes generous free egress each month — a multiple of what you store — and downloads served through Cloudflare are free under Backblaze's partner egress. For an email archive, which you rarely bulk-download, restores stay inexpensive or free.
Is backing up email to B2 the same as Amazon S3?
Effectively yes — B2 is S3-compatible, so InboxBucket uses the same connector pointed at your B2 endpoint. If you're comparing destinations, the Amazon S3 setup applies directly; B2's draw is lower storage cost and a company built on backup.
What format are the backups in?
Every email is stored as a .eml file — the standard RFC 822 message with headers, body, and attachments in one portable file that opens in any mail client or a text editor. No proprietary format, nothing to export later.
Free plan · No credit card
Put your email in your own B2 bucket.
Add your bucket, get your address, and the next email you forward is written to low-cost storage you control.
Add your B2 bucket