Lark Mail Warm Up: Safe Setup for Outreach

Warm up Lark Mail by enabling IMAP/SMTP, using a mail-client password, publishing SPF, DKIM and DMARC, then ramping from 3 to 30 warm-up emails per day. Skip DNS or increase volume too fast, and Gmail, Yahoo, Microsoft and corporate filters can treat you as untrusted. This guide gives the setup, checks and safe ramp.

Lark and Feishu still need the same sender authentication, gradual volume and engagement history as any outreach mailbox. If you want a free setup, BobWork Email Warm-up supports Lark through IMAP plus a mail-client password.

What does Lark need first?

Lark is your sending platform. It is not the only system judging your mail. Recipients on Gmail, Yahoo, Microsoft, Zoho, iCloud and company gateways evaluate your domain, mailbox history, pattern and recipient reactions.

Start with the checks receivers can verify before they read your copy.

Google tells senders to keep spam complaints below 0.1% and avoid ever reaching 0.3%. Use that as an operating rule even when Lark is your sender. Yahoo also expects authenticated, wanted mail. Read the primary requirements from Google and Yahoo Sender Hub before sending meaningful volume.

Warm-up does not fix bad targeting. It creates normal mailbox activity before campaigns. If your lists are scraped, stale or badly matched, you can still land in spam after a clean technical setup.

How do you set up access?

The setup has two parts. The admin must allow mail-client access. Then each user creates a password made for IMAP and SMTP. Do not use the normal login password when Lark provides a mail-client password.

Enable IMAP and SMTP

In the Lark Admin Console, go to Admin Console → Products → Mail. Find the third-party client, IMAP or SMTP settings. Enable access for the users or organisational unit that will send outreach.

If your tenant is on Feishu in China, use the equivalent Feishu Admin Console path. The wording can vary, but the setting belongs under the Mail product area.

Use the current values shown by your tenant. These are the common client settings to check against:

If login fails, check the admin switch before changing DNS. Early failures usually come from disabled client access, wrong tenant server names or using the normal account password.

Generate the mail-client password

Open the user mailbox. Go to the mail settings area for third-party email clients. Generate a mail-client password, app password or dedicated client password. Copy it once and store it securely.

Use the full mailbox address as the username. Use the generated password for IMAP and SMTP. Keep two-factor authentication enabled if your organisation requires it.

Connect the mailbox

Test IMAP first. A working IMAP connection proves the tool can see warm-up messages that land in Inbox or Spam. Then test SMTP. A working SMTP connection proves the mailbox can send.

BobWork connects Lark through IMAP plus the mail-client password. By default the mailbox warms in the shared network; switch the account to Private pool and only your own mailboxes write to each other (at least two needed). The engine handles sending, replies and spam rescue automatically.

Warm-up should not read, move or answer real mail. In BobWork, only mail carrying the engine's hidden header is touched. Lark warm-up mail found in Spam is moved to Inbox, marked read, labelled Warm-up and archived after 24 hours.

For timing, weekends and reply limits, see how the warm-up engine works. If this is your first mailbox, read what to expect during warm-up before judging the first few days.

Which DNS records must pass?

Do DNS before volume. SPF, DKIM and DMARC tell receivers that Lark is allowed to send for your domain and that messages can be authenticated.

SPF is defined in RFC 7208. DMARC is defined in RFC 7489. The practical work still happens in your DNS host and your Lark or Feishu admin setup screen.

For SPF, copy the current include value from Lark or Feishu. Lark commonly uses a Lark sending include, but provider values can change. Do not paste an example when the admin screen gives you a different value.

You should have only one SPF TXT record at the root domain. If you also send through another platform, newsletter tool or website mailer, merge the includes into one record. Use the free SPF checker after publishing.

For DKIM, copy the exact host and value from the admin setup. The selector may look like a Lark or Feishu selector, but do not guess. Some DNS hosts want only the host prefix. Others want the full host name. Verify it with the free DKIM checker.

For DMARC, start with p=none while you are setting up. This lets you receive reports without blocking legitimate mail by mistake.

v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

Use an address that can receive mail. Later, after all legitimate senders align, you can move to quarantine or reject. Check the exact sending domain with the free DMARC checker, especially if outreach uses a subdomain.

What ramp should you follow?

A safe ramp should look boring. BobWork starts at 3 emails per day, adds 2 per day, caps at 30 per day by default, and runs weekends at 30%. The cap is editable per mailbox up to 100, but cold outreach usually should not need that.

Sends are spread between 09:00 and 18:00 in the mailbox's own time zone. The engine decides every 15 minutes with randomness. A pair never writes to each other twice within three hours. Peers on another domain or provider are picked twice as often.

About 40% of received warm-up mail gets a reply. Threads end after three messages. Content is plain office talk, in plain text, with no links and no images.

Use this schedule for a normal Lark Mail warm-up:

Use three to four weeks for a new domain. New domains have no sending history, so the second half of the ramp matters. Day 14 is a minimum for existing domains, not a permission slip to blast.

During campaigns, keep warm-up at 10–15 emails per day. Keep real outreach around 30–50 emails per mailbox per day. Add mailboxes rather than forcing one mailbox to carry all volume. For planning, use the warm-up schedule generator.

What breaks Lark warm-up?

Most Lark warm-up failures come from access settings, DNS mistakes or volume jumps. Check these before blaming the mailbox.

IMAP login fails. Confirm IMAP/SMTP is enabled in Admin Console → Products → Mail. Then check the tenant server name. Use the full email address as the username. If needed, regenerate the mail-client password and paste it without spaces.

SMTP sends fail. Try the other supported SMTP mode. Some clients work better with port 465 and SSL/TLS. Others expect port 587 with STARTTLS. If both fail, ask the admin whether outbound client sending is restricted by department, group or policy.

SPF has two records. Two SPF records can cause SPF evaluation to fail. Merge includes into one record and keep it under the DNS lookup limit. Test the final record before sending.

DKIM uses the wrong selector. DKIM fails when the DNS host does not match the selector in Lark or Feishu. Copy the host exactly. Do not add the domain twice.

Warm-up lands in spam. Some spam landings are normal early. Watch the seven-day trend, not one message. In BobWork, spam rate is the share of a sender's warm-up mail that receiving mailboxes found in Spam over seven days.

Pause a mailbox for a few days if spam rate rises above 5%. Then check SPF, DKIM, DMARC and blacklist status. The email blacklist checker can help rule out a domain or IP listing.

Outreach starts too early. Warm-up is preparation, not permission to send 100 cold emails per day from one new mailbox. For more diagnosis, use the causes in why emails go to spam.

What should you verify now?

Use this checklist before the first campaign from Lark Mail or Feishu Mail.

A setting is not done because you added it. It is done when a login test, DNS checker or mailbox metric proves it works.

When is Lark ready?

A Lark mailbox is ready for controlled outbound when the technical setup is clean and the warm-up history is stable.

BobWork marks a mailbox ready for outbound when it has warmed for 14+ days, has a seven-day spam rate of 3% or lower, and has received at least 30 warm-up emails. Health is 0–100: Healthy is 85 or higher, Watch is 60–84, At risk is below 60, and Blocked means login or permission failed.

Once ready, start with your best list. Send to people who are likely to recognise the topic. Keep the first week small. If replies and delivery look stable, increase carefully.

If you warm multiple Lark mailboxes, do not put them all on the same new domain at high volume. Keep sane per-mailbox limits and keep warm-up running in the background.

You can warm Lark Mail free with BobWork Email Warm-up at emailwarmup.bobwork.ai. It is free, needs no credit card, has no time limit, and supports up to 20 mailboxes per account. Lark connects through IMAP plus a mail-client password. Outlook and Microsoft 365 are not supported yet.

Frequently asked questions