How to Warm Up 200 Mailboxes for Cold Email

To warm up 200 mailboxes in BobWork Email Warm-up, a new account pays $380/month: 10 free mailboxes and 190 paid extras. If you skip domain planning, DNS checks, CSV testing, and a safe ramp, the fleet becomes hard to debug. This guide gives the setup order, CSV format, ramp maths, pool choice, and daily checks.

At this size, you are not managing one inbox. You are operating domains, credentials, DNS, warm-up volume, spam landings, billing, and readiness across a fleet.

You can start the first 10 mailboxes with the free email warm-up tool, then keep the same account when you import the other 190. If you are preparing rows now, keep the CSV bulk import guide open while you work.

What does 200 cost?

A new BobWork account includes 10 free active mailboxes. At 200 active mailboxes, you have 190 paid extras. The listed monthly cost is $380.

Billing is per active mailbox above the free allowance. Extras are billed by Stripe, prorated, and can be cancelled any time. If extra mailboxes are paused, they do not bill.

The free plan changed on 27 October 2026. New accounts get 10 free mailboxes. Earlier users keep 20 free mailboxes for as long as they use the service. At this fleet size, earlier users pay $20 less than the new-account prices below.

The default account limit is 200 mailboxes. That makes 200 the largest normal fleet you can set up without asking for a higher cap.

If you need 500, 1,000, or more, request a higher account limit at info@bobwork.ai. Larger fleets need tighter domain planning and usually a private pool.

How do you warm up 200 mailboxes?

Do the setup in this order: domains, DNS, credentials, test rows, CSV import, pool mode, ramp monitoring. Do not connect 200 inboxes before the domains are ready.

For 200 mailboxes, use typically 2 to 5 mailboxes per domain. That gives you a planning range of 40 to 100 domains.

That range is not a deliverability guarantee. It spreads risk without making DNS, billing, and mailbox administration unmanageable.

Do not put 200 cold-email mailboxes on one domain. Warm-up cannot fix that concentration risk. If one domain fails authentication, receives complaints, or hits provider limits, too much of the fleet is affected at once.

Each domain needs SPF, DKIM, and DMARC. Gmail and Yahoo sender rules expect authentication for bulk sending. Google also says spam complaint rates should stay under 0.1% and never reach 0.3% in its email sender guidelines.

Yahoo requires SPF and DKIM, DMARC at least p=none and passing, aligned From domains, one-click unsubscribe for bulk senders, and spam rates under 0.3%. Check the current wording in Yahoo sender best practices.

BobWork checks SPF, DKIM, and DMARC daily and shows results per domain. For SPF, avoid too many DNS lookups. SPF has a 10-lookup limit. If a domain uses several senders, use the SPF 10-lookup guide before you scale.

For DKIM, confirm the selector is present. BobWork looks for common selectors including google, zmail, default, selector1, selector2, k1, s1, mail, dkim, lark, feishu, and zoho.

For DMARC, start with p=none if you are still observing alignment. The record must exist, and your sending domain must align with SPF or DKIM for provider rules that require alignment.

If you are still separating domain reputation from mailbox reputation, read domain warm-up vs mailbox warm-up. At 200 mailboxes, both matter.

Which providers work?

BobWork supports Gmail and Google Workspace, Zoho Mail, Lark Mail, Yahoo Mail, iCloud Mail, Amazon SES, SendGrid, Mailgun, and any IMAP plus SMTP mailbox.

BobWork does not support Outlook or Microsoft 365 yet. Microsoft requires OAuth. If your 200-mailbox fleet is Microsoft-only, do not plan this setup around BobWork until Outlook support is live.

For Gmail or Google Workspace, the recommended route is IMAP with an app password. Google app passwords require 2-Step Verification. Google documents the setup on its app password help page.

BobWork also has one-click Google sign-in, but Google caps unverified apps at 100 users and shows an unverified-app notice. For a 200-mailbox build, IMAP app passwords are usually the cleaner route.

For Yahoo and iCloud, use app passwords. For Zoho, BobWork can use the Zoho Mail API via a Self Client code, including on Zoho’s free plan, or IMAP on Mail Lite and above.

Use the provider guide before you upload rows: Google Workspace warm-up, Gmail bulk accounts, Zoho Mail warm-up, Yahoo Mail warm-up, or iCloud Mail warm-up.

How do you upload 200 rows?

Use the bulk importer instead of adding each mailbox by hand.

In the dashboard, go to Add mailbox → Many mailboxes: upload a CSV. You can paste rows or upload a file.

Use these columns:

For Gmail, Yahoo, and iCloud, the hosts are filled in. For other domains, add imap_host. If the provider is not a preset, connect it as an IMAP plus SMTP mailbox.

Every row gets the same IMAP and SMTP login test as a single mailbox connection. Failed rows are listed with the reason. Already-connected rows are skipped, so you can fix a CSV and re-upload it safely.

Mailboxes above the free limit need billing active before they connect. At 200 mailboxes, billing should be active before most rows can be accepted.

Before the full import, test three rows manually. Use one mailbox from each major provider or domain pattern. This catches app password, IMAP host, SMTP permission, and DNS mistakes before you create a 200-row failure report.

For Google Workspace, confirm 2-Step Verification is enabled where app passwords are required. If your security policy blocks app passwords, fix that policy before bulk upload.

If you manage imports through scripts, BobWork also has an email warm-up API. The API can connect IMAP and Zoho mailboxes, read warm-up stats, and check SPF, DKIM, and DMARC. The API is free; paid sends triggered through other features use credits.

What does the ramp look like?

Each mailbox ramps independently. The engine starts at 3 warm-up emails per day, adds 2 per day, and caps at 30 per day. The cap is editable per mailbox, up to 100.

For cold-email fleets, do not raise the cap just because you can. Published practice is to keep warm-up at 10 to 15 per day during active campaigns and real outreach at 30 to 50 per day per mailbox.

The table below shows the standard weekday ramp for 200 mailboxes. Weekends run at 30% volume.

The engine spreads sends across 09:00 to 18:00 in each mailbox’s own time zone. It decides every 15 minutes with randomness. A pair never writes to each other twice within 3 hours.

Peers on a different domain or provider are picked twice as often. That matters for a 200-mailbox build. A 40 to 100 domain spread gives the engine more internal variety than a small cluster of domains.

About 40% of received warm-up mail gets a reply. Threads end after 3 messages. Content is plain office talk: plain text, no links, no images, and first-name greetings.

Spam rescue is limited to warm-up mail. If warm-up mail lands in Spam, the engine moves it to Inbox, marks it read, labels it Warm-up, and archives it after 24 hours. It only touches mail carrying the engine’s hidden header, or a known subject for Zoho API senders. Real mail is never read, moved, or answered.

Should you use a private pool?

BobWork uses a shared warm-up network by default. Every active mailbox on the service exchanges warm-up emails with other active mailboxes across accounts. One mailbox is enough to start.

At 200 mailboxes, use a private pool unless you have a reason to stay in the shared network.

Private pool is set per account in Mailbox pool → Pool mode. In private mode, only your own mailboxes warm each other, and nobody outside the account receives their addresses. A private pool needs at least two mailboxes.

The warm-up engine handles pairing and spam rescue automatically in either mode. The difference is who your mailboxes can exchange messages with.

Private mode does not protect weak infrastructure. Bad DNS, poor lists, high bounce rates, or aggressive outreach can still hurt performance.

If you run multiple clients, do not mix unrelated clients in one private pool unless you deliberately want their mailboxes warming each other. A cleaner agency setup is to group mailboxes by account, client, or operating unit.

Which metrics matter daily?

Do not judge a 200-mailbox fleet by one average. Averages hide failing domains, blocked mailboxes, and providers that need attention.

BobWork measures spam landings directly in the receiving mailbox. It does not use third-party seed lists. Spam rate is the share of a sender’s warm-up mail that receiving mailboxes found in Spam over 7 days.

Read results at three levels: mailbox, domain, and fleet.

Blocked means login or permission failed. Treat blocked mailboxes as operational failures, not deliverability signals.

Ready for outbound is per mailbox. A mailbox is ready only after 7 or more days warming, a 7-day spam rate of 3% or less, and at least 30 warm-up emails received.

For cold campaigns, add mailboxes rather than pushing one mailbox harder. New domains should warm for 2 to 3 weeks. Existing domains often need at least 7 days.

If you send from the same mailboxes you warm, keep warm-up running. The warm-up while sending guide explains the operating pattern.

If you use BobWork Outbound, only mailboxes that pass the ready gate can send. In their first week after ready, they cap at 30 cold emails per day. After that, they cap at 50 per day. Warm-up continues on the same mailboxes while they send.

You can also use warm-up alone and send campaigns elsewhere.

What should you do now?

Use this checklist before you import 200 rows. It is shorter than debugging 200 broken mailboxes after the upload.

A 200-mailbox warm-up project is mostly preparation. The CSV import is fast. The work is clean DNS, app passwords, domain spread, pool choice, and daily review.

To run it in BobWork Email Warm-up, start with the first 10 mailboxes free, confirm the DNS checks, then upload the full CSV when billing is active. For 200 active mailboxes, the new-account cost is $380/month, with shared warm-up by default and private pool available in the dashboard.

Frequently asked questions