Mailshake to lemlist: A Safe Migration Plan for 2026

Why teams outgrow Mailshake (and when migration makes sense)

lemlist gives you a built-in 600M+ lead database, data enrichment, intent-based triggers, and true multichannel sequencing in a single workflow. Mailshake keeps things simpler and cheaper, with straightforward cold email and phone plus LinkedIn on its top tier. So why do teams switch?

The short answer: their outbound motion outgrew what Mailshake can support natively. Mailshake’s personalization features are basic compared to lemlist, it has no native multichannel (email + LinkedIn in one sequence), and the UI is dated next to modern alternatives. Once you’re bolting on two or three separate tools just to cover LinkedIn, enrichment, and phone, the question stops being “Is Mailshake good enough?” and becomes “Am I spending more time managing my stack than selling?”

Here are the signals that usually push a team toward migrating:

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  You’re stitching tools together for every channel. Mailshake handles email well, but if you’re also running a LinkedIn automation tool, a standalone dialer, and a separate enrichment vendor, you’re managing four logins to do one job.

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  Reply rates have plateaued. Mailshake supports merge tags, spintax, and basic AI templates but not custom intro images, embedded video, or dynamic landing pages. If you’ve hit a personalization ceiling, adding channels and richer personalization often breaks the plateau.

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  You want one place for lead sourcing, enrichment, and outreach. Switching between a data vendor, a cleaning tool, and a sending platform means slower campaign launches and more room for errors in the handoff.

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  Deliverability monitoring feels reactive. You find out about spam placement after reply rates already dropped, rather than catching it early with inbox placement tests and automated alerts.

Migration is worth the effort only when the gap between what you have and what you actually use day to day is costing you pipeline. If Mailshake is working and your motion is email-only, there may be no reason to move.

What Mailshake features map to in lemlist

Before you touch a single CSV, take a few minutes to understand where each Mailshake workflow lands inside lemlist. This saves you from rebuilding something that already has a direct equivalent, and it reveals new capabilities you didn’t have before.

You’ll notice that most Mailshake features have a 1:1 equivalent. The difference is that lemlist bundles them with additional channels and data layers, so you end up with fewer tools to maintain.

The pre-migration audit checklist

Migrations fail when teams skip the inventory step. You want a complete picture of what you’re moving before you start setting up the new platform. Here’s what to document:

Campaigns and sequence performance data. List every campaign (active, paused, and completed). Record open rates, reply rates, and bounce rates per sequence. These become your benchmarks for comparison after the switch.

Prospect lists and custom fields. Mailshake allows you to export your data from selected campaigns in a few different ways, including prospects (all prospects and their information, as well as records of sends, opens, and other metrics). Document every list, segment, and custom field name you use. Flag any non-standard field names (like “custom_1” instead of “jobTitle”) that will require mapping during import.

Sending infrastructure and domain authentication. Write down every sending domain, connected mailbox, and authentication record (SPF, DKIM, DMARC). Confirm these are healthy before migrating so you don’t carry broken infrastructure into the new platform.

Active integrations and webhooks. Catalog every integration: CRM connections, Zapier workflows, Slack notifications, webhook endpoints. Note which ones you’ll rebuild in lemlist and which stay connected via the same CRM or API.

How to export everything from Mailshake

Mailshake doesn’t have a one-click option to export all prospects. You’ll pull data in pieces, campaign by campaign. Here’s the order that keeps things clean.

1. Export prospects and engagement data campaign by campaign

Click Campaigns in the left side menu, select the campaigns you want to export (up to 20 at a time), click Export in the grey menu bar, select the option you’d like to export, and once the export is done processing, click Download CSV. Choose the Prospects export to get contact info alongside engagement columns (opened, replied, bounced). This lets you filter out unresponsive or bounced contacts before importing into lemlist.

2. Export sent messages and reply logs

From the same export menu, select Sent Messages instead of Prospects. The Sent Messages export will show you how many times a prospect opened your email or clicked a link, along with the dates of replies, bounces, and unsubscribes for each prospect. Keep this file for reference and compliance records.

3. Download list cleaning results

Mailshake also lets you export list cleaning results. If you used Mailshake’s list cleaner, grab those results so you don’t accidentally re-import addresses that were already flagged as invalid.

4. Document sequence copy and settings manually

Mailshake doesn’t export email templates as structured files. Copy each email step’s subject line, body, and sending schedule into a Google Doc or spreadsheet. Note any A/B test variants and the delay intervals between steps. This feels tedious, but it’s worth the ten minutes per campaign.

Setting up lemlist before you import anything

Get your infrastructure right before any data touches the platform. This is the foundation everything else depends on.

1. Connect or buy sending domains

You can add your existing sending domains or purchase new ones directly inside lemlist. lemlist’s Deliverability Hub and lemwarm setup help your emails keep landing as you send across many mailboxes and domains. Authentication (SPF, DKIM, DMARC records) is configured automatically when you connect, so there’s no manual DNS editing required.

2. Start lemwarm on every mailbox

lemwarm is lemlist’s built-in warm-up tool. It exchanges real emails across a network of more than 10,000 real accounts and generates human-like content for each message, so your inbox builds a reputation through genuine conversations rather than fake traffic.

Warm-up runs in two phases before any campaign: roughly 2–3 weeks of ramp-up to reach your target volume, then 2 weeks of stabilization with no spam, so about one month in total. Only begin outreach once your Warmup Score reaches 90+, lemwarm shows no spam, and your inbox rate has stayed above 90% for 14 straight days (see lemlist’s guide to setting up lemwarm). Start lemwarm the moment you connect your mailboxes, even if you’re weeks away from sending.

3. Connect your CRM

Link HubSpot or Salesforce so that lead data, activity logs, and deal updates sync from day one. lemlist also supports API and MCP access for custom setups with tools like Claude or Cursor.

4. Configure sending schedules and daily volume caps

Set sending windows matched to your prospects’ time zones and cap daily volume per mailbox at a safe level during ramp-up. lemlist enforces these automatically, but setting them intentionally (rather than accepting defaults) gives you more control over how fast you scale.

How to import Mailshake data into lemlist

Your exported CSVs are only useful if they’re clean and correctly mapped. Here’s the process, step by step.

1. Clean and format exported CSV files

Remove bounced, unsubscribed, and duplicate contacts before import. lemlist’s CSV structure expects Row 1 to contain column names (email, firstName, companyName, etc.) and Row 2 onward to contain lead data, one lead per row. If your first row contains an actual email address, lemlist treats it as a column name and skips that lead (see lemlist’s CSV import guide).

2. Map Mailshake columns to lemlist variables

lemlist recognizes default variables like {{email}}, {{firstName}}, {{lastName}}, {{phone}}, {{linkedinUrl}}, {{companyName}}, and {{icebreaker}} (see lemlist’s guide to choosing the right CSV import type). During import, you’ll assign each CSV column to the correct lemlist variable type.

Columns not assigned to a default type become custom variables, named after their column headers. So if your Mailshake export has a column called “Industry,” it becomes {{Industry}} in lemlist. Keep in mind: custom variables are case-sensitive, so {{firstName}} and {{firstname}} are different (the lemlist academy lesson on custom variables covers this in detail). Getting this mapping wrong breaks personalization in your campaigns, so double-check it before continuing.

3. Run enrichment on import to fill data gaps

After import, you can use lemlist’s waterfall enrichment to fill missing emails, phone numbers, and LinkedIn URLs. This queries multiple data providers per contact rather than relying on one source, closing gaps that existed in your Mailshake data without a separate vendor.

4. Deduplicate and verify before launching

Run lemlist’s built-in email verification to catch any remaining invalid addresses. Deduplication prevents the same prospect from receiving outreach from multiple campaigns, which is especially common when you’re combining exports from several Mailshake campaigns.

Rebuilding Mailshake sequences as multichannel campaigns

Here’s where migration turns from admin work into an opportunity. Instead of recreating your old email-only sequences identically, use the switch to add the channels Mailshake couldn’t support natively.

Take a typical Mailshake 4-step email sequence. In lemlist, you might keep steps 1 and 3 as emails, insert a LinkedIn connection request after step 2 (triggered if there’s no email reply), and add a call step or SMS follow-up at step 4. lemlist’s conditional logic lets you branch based on engagement: opens, clicks, replies, or even whether a LinkedIn request was accepted.

A few decisions to make for each sequence:

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  Which steps stay as email, and which become LinkedIn, call, or SMS touches

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  Where to insert conditional branches based on engagement signals

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  How to adapt your Mailshake A/B test variants into lemlist’s A/B framework

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  Whether to use AI-generated personalization variables (like custom icebreakers pulled from LinkedIn profiles) to replace the generic merge tags you used before

You don’t have to go multichannel on everything. Start by upgrading your highest-performing sequence, measure the difference, and then expand from there.

Protecting deliverability during the switch

The biggest risk of any platform migration is a sudden reputation drop. You’re essentially starting from scratch on a new sending platform, and inbox providers don’t know you yet. Here’s how to manage that.

The parallel-run strategy. Run Mailshake and lemlist side by side for two to three weeks. Keep active Mailshake campaigns going while you test new campaigns in lemlist with small segments. This avoids a cold start and gives you real performance data to compare.

Warmup timelines and volume ramp. The sweet spot for warming a new address is about one month: 2–3 weeks of ramp-up, then 2 weeks of stabilization. Start with low daily volume from lemlist, increase gradually as lemwarm builds reputation, and resist the temptation to migrate all volume on day one. If you’re using existing (already-warmed) mailboxes and simply connecting them to lemlist, the ramp is shorter, but you still want to ease in.

Monitoring inbox placement from day one. lemlist’s Deliverability Hub lets you run inbox placement tests by sending to real test addresses across Google, Microsoft, and other providers. You can see whether your emails land in the primary inbox, promotions, or spam before you scale up. Set up automated alerts for bounce spikes or spam placement so you catch problems before they compound.

A 4-week migration timeline that keeps pipeline alive

This timeline assumes you’ve already completed the audit from the checklist above. Adjust it based on your team size and number of active campaigns.

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  Week 1 (infrastructure and warmup): Connect domains, start lemwarm, link your CRM, set sending schedules. No outreach yet. Focus entirely on getting the technical foundation right.

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  Week 2 (data migration and first test campaign): Import cleaned CSVs, map variables, run enrichment. Launch one low-volume test campaign to a small segment and monitor deliverability closely.

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  Week 3 (full campaign rebuild and parallel run): Rebuild remaining sequences as multichannel campaigns. Run lemlist campaigns alongside still-active Mailshake campaigns. Compare performance side by side.

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  Week 4 (cutover and Mailshake decommission): Pause remaining Mailshake campaigns. Move all volume to lemlist. Confirm CRM sync is capturing all activity. Cancel or downgrade Mailshake once you’ve validated everything works.

Migrating between Mailshake and lemlist takes 1 to 2 days per active campaign template, so for a team with five or six active campaigns, this four-week window gives you enough room to be methodical without stalling pipeline.

Post-migration validation and common mistakes to avoid

After the switch, check four things: deliverability metrics in the Deliverability Hub, reply rates compared to your Mailshake benchmarks, CRM data integrity (are all activities syncing correctly?), and inbox placement scores across your sending domains.

The mistakes that trip most teams up:

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  Migrating bounced or unsubscribed contacts and damaging sender reputation on the new platform before you’ve sent a single real campaign

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  Skipping warmup and sending full volume from lemlist on day one, which triggers spam filters immediately

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  Not mapping custom fields and sending emails with broken personalization (nothing kills reply rates like “Hi {{custom_1}}”)

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  Forgetting to update webhook endpoints so CRM or Slack notifications break silently, and your team doesn’t realize for days

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  Abandoning Mailshake too early before confirming lemlist campaigns perform at the same level or better

A clean migration is one where your prospects never notice a thing changed on your end.

Your outbound runs better after migration, not just the same

Migration is the right moment to fix what wasn’t working. If you move to lemlist and only rebuild the same email-only sequences you ran in Mailshake, you’ve done the work without capturing the upside. Multichannel campaigns, intent signals that trigger outreach when prospects are actually ready to engage, AI enrichment that pulls context from LinkedIn and websites, the Deliverability Hub that monitors inbox placement in real time: these are the things that make the switch worthwhile, not just switching logos on your dashboard.

Start a 14-day free trial to test your migration plan before committing. No credit card required, cancel anytime. Or book a demo if you want a walkthrough of how your specific Mailshake setup would map to lemlist.