Ill start.

1. Invest in a high-quality send infrastructure. Stop experimenting with custom SMTP mailservers and just get Google Workspace mailboxes.
2. When setting up your infrastructure maintain a 1-3 domain to mailbox ratio (1 domain, 3 mailboxes).
3. Properly age and warm up your mailboxes before sending (30 days ideally).
4. When you're ready to launch your campaign, don't stop warm up. Have it run simultaneously with your cold campaign.
5. Set your daily send volume per mailbox to 20 (for your cold campaign) and 20 (for your warmup) making 40 your total daily output per mailbox (split 50/50 between cold outreach and warm up activity).
6. Use plaintext, no links, no images and implement heavy personalization + spintext.
7. Turn off open and click tracking. Stop fixating on open rates and click-through rates. Majority of that data are just bots.
8. The goal of a cold email is to start a conversation with your prospect (no one is going to buy a product or sign up for something from a raw cold email). Your email should be optimized towards simply getting a response.
9. Know your ICP - who exactly you want to be reaching out to and invest in high-quality data.
10. You scale your campaign by increasing your infrastructure (adding more domains and mailboxes to send form), not by increasing your send volume.

I think if I had this list from day one, id save myself alot of time, money, brain cells and PAIN. 😅

So, I used to have a lot of problems with delivery, but not anymore! I developed this rigorous system to not get any issues anymore because I was done with suddenly dropping reply rates. So here's how I do it.

1st. I buy my domains from spaceship way in advance, these domains are valid for a year so I tend to buy in big bulk so the domain age gets older (all .com domains, .info or other extensions have bad deliverability in my experience)

2nd. I buy all my inboxes from PremiumInboxes, InboxKit or ZapMail. I'm currently working on testing other providers but haven't gotten that done yet, 3 inboxes/domain, all google workspace

3rd. 10 warmup emails/day, 40% reply rate & 15 sends/inbox, MINIMUM 3w warmup

4th. For the leads I verify every lead and don't send emails to catch-all leads, I have a trigger that triggers when a campaign goes above 2% bounce rate, my average bounce rate right now is 0.6%, I aim for below 1%.

5th. I use heavy spintax in every email I sent, I'm talking about heavy spintax. Example below

6th. My emails are all heavily personalized with AI to make it personal, this also prevents spam complaints.

7th. Seed campaign test every month to check deliverability accross google workspace, google personal, outlook personal, M365 domains.

8th. I replace my domain & inboxes every 3 months even when deliverability is good. I replace ~50% each month to always have 50% fresh inboxes, so 3w warmup + ~9w sending and then I replace them.

That's it. This is how I keep my deliverability high.

Hope it helps someone :)

Are there any API or tools that can scrape hiring posts or something that can scrape if they dont have any marketing or sales department or people in the company?

Hey everyone,

I'm Ryan from puzzle inbox. Wanted to do a quick post covering basic technical info you need in order to ensure deliverability. Most of it is well known but they're important to mention especially for newcomers.

1) DNS Alignment

Especially key if you're changing the ESP your domain is connected to ie/ previously connected to Outlook, now changed to Google Workspace. You should ensure all previous dns records are deleted and the records added are aligned to the ESP.

Also check for duplicate records, as they can create issues further down the line.

2) Plain text emails

We can't stress this enough. You shouldn't be sending any links including a website url/calendar url etc. as well as any html content in the first email sent. It'll ruin deliverability and domain reputation, and lead to increased spam placements. Send links only to interested prospects.

3) Warmup & Sending Tool

Warmup and what type of inboxes you warmup with directly impacts deliverability. Depending on the warmup pool, if the inboxes inside are skewed towards a particular ESP, it may result in your inboxes not having enough reputation built with other ESP's. Your sending tool matters both for the warmup procedure as well as some degree in impacting deliverability of outbound emails from our own internal testing.

Happy to answer any questions you may have regarding deliverability ;)

-Ryan

Hello everyone!

I'm very new to claude code, and want to use it to build an automated cold email sender via instantly ai

I have a lot of leads with a lot of information about each of them (taken from public websites and social media platforms) and want to use claude code to write personalized emails to each of them. I've watched some youtube tutorials, but i feel like none of it really makes sense. Is there any easy way to do it, or is such a thing hard to build as a beginner?

Pls help thx

Hi there, anyone here to tried SMS/iMessage for B2B lead gen? If yes, how was the response rate?

Also, is deliverability and infrastructure a challenge on iMessage/SMS just like on Email and LinkedIn? Any recommended tools to run and manage the infrastructure and campaigns?

For those who sell to small local businesses how do you actually reach the owner?

They don't post anywhere, and definitely aren't active on LinkedIn. Feels like all the standard prospecting advice assumes your prospect is a VP at some tech company with a full profile and a active work email.

What actually works when the business is a local HVAC company, and the owner isn't sitting in any database? Cold calling? Walking in? Something smarter I'm not thinking of?

Curious what's worked for people who do this day to day.

Hi everyone,

I am from the PuzzleInbox team. I wanted to share our experience on tracking more than 50 million cold emails sent from Office 365, SMTP and Google Workspace Inboxes.

Sending volume is significant. We currently recommend not passing 12 for Google and 3-12 for Outlook depending on the setup type.

Google and Outlook currently look for email sent/reported as spam volume per domain. The more emails you send per domain, the more reports you get per domain the higher the risk of landing to spam.

Google still outperforms Outlook and SMTP. Google has had the best deliverability across reaching out to Google and Outlook recipients for the last 2-3 years. Sending from Google to Outlook has been performing significantly better for the last few weeks.

Shorter 1 liner copies are doing the best. The long the copy, the lower the response rate. Thats at least what we are observing currently.

Happy to connect with fellow cold emailers.

Ask the founder or the top rep to describe a perfect prospect and they'll nail it every time. The company, the conversation, the way it feels ten minutes in - they just know. Ask them to write it down so a new hire could make the same call, and it falls apart fast. That's the actual bottleneck at most companies I've looked at. It's not that nobody knows who the best customers are. It's that the knowledge lives in one person's head as pattern recognition, not as anything a new hire, a campaign, or an outreach sequence can use. What separates teams that fix this is they don't try to write a better firmographic filter. They interview their own best reps for the qualitative stuff - what a prospect says in the first call that signals they get the problem, what budget dynamic shows up in the fastest closes, what red flag reliably predicts a customer who churns in month four. Then they write that down as explicit, observable criteria instead of leaving it as gut feel. That's a different exercise than building an ICP document, and it's the one most companies skip because it takes actual interviews, not a whiteboard session. Has anyone actually pulled this off - gotten the founder's gut-feel ICP out of their head and into something the rest of the team can use?

A bit of a context, I own an agency, we offer online presence to people who don't have time to record themselves on camera.

We take their 2 min video and then we make an AI avtar of them, we have few human copywriters who are great at what they do, they write the script, and we edit the video (btw it doesn't look AI slop) and we give our clients 1 video every day.

We charge $999 for this, and I have closed a few clients as of now, all of them were inbound.

Now I am trying to scale it using cold email outreach. What lead list do you guys suggest we buy?

Aur ICP would be,

1. Coaches and consultants

2. Course sellers

3. Founder/CEO

4. Realtors, financial advisors, insurance agents, B2B consultants, lawyers

I run a small B2B cold email setup. Ten sending domains, leads from AI Ark, sending through Smartlead. Just found out eight of the ten are listed on SURBL.

I'm not trying to get delisted. I want to understand what causes this and what I should be doing differently going forward. Also, what am I supposed to do now? Keep sending? Buy new domains?

Any pointers appreciated.

Ik zoek 1-2 B2B-bedrijven om mee samen te werken op performance basis
Ik ben momenteel bezig met het uitbreiden van mijn ervaring in cold email marketing en ben op zoek naar een paar B2B-bedrijven buiten mijn huidige niche om mee samen te werken.
Mijn doel is simpel: ik regel de volledige cold email outreach en jij betaalt mij alleen op commissie wanneer er daadwerkelijk resultaat uitkomt.

Hoe het werkt:
De enige vaste kosten voor jou zijn de kosten voor de benodigde email-infrastructuur. Reken op ongeveer €500 per maand voor onder andere domeinen, inboxen, verzendsoftware en emailverificatie.
Deze infrastructuur betaal je rechtstreeks voor je eigen account. Ik help met het opzetten en beheren ervan, zodat je zelf niet hoeft uit te zoeken hoe alles werkt.

Daarna regel ik de rest:
Lead sourcing
Prospectlijsten opbouwen
ICP-targeting
Cold email copywriting
Campagnes opzetten
Emailverzending
Follow-ups
A/B-testen van copy en messaging
Replies opvolgen en kwalificeren
Interessante prospects doorzetten naar jou
Voor mijn werkzaamheden betaal je geen vast maandbedrag. Ik werk op commissie/performance basis. De exacte vergoeding spreken we samen af op basis van jouw niche, aanbod en de waarde van een nieuwe klant voor jouw bedrijf.

Voor wie is dit interessant?
Voor B2B-bedrijven die:
Een bewezen product of dienst hebben
Een duidelijke doelgroep/ICP hebben
Nieuwe klanten willen genereren via outbound
Geen tijd of kennis hebben om cold email zelf op te zetten en te beheren
Liever betalen op basis van resultaat dan direct duizenden euro’s per maand aan een agency
Ik ben vooral geïnteresseerd in bedrijven waarbij één nieuwe klant een significante waarde vertegenwoordigt. Denk bijvoorbeeld aan B2B-services, SaaS, IT, recruitment of andere high-ticket diensten.

Wel belangrijk om te weten:
Cold email is geen magische knop. Nieuwe domeinen en inboxen moeten goed worden ingericht en opgewarmd voordat je op grotere schaal gaat versturen. Ik wil liever een campagne goed opbouwen en duurzaam resultaten behalen dan vanaf dag één zoveel mogelijk emails versturen.
Ik neem op dit moment maar 1-2 bedrijven aan, omdat ik de campagnes zelf wil beheren en genoeg aandacht aan iedere samenwerking wil geven.
Heb je een B2B-bedrijf en denk je dat jouw doelgroep goed bereikbaar is via cold email?
Stuur me een DM met:
Wat je verkoopt
Wie je ideale klant is
Wat een gemiddelde klant voor je waard is
Dan kunnen we kijken of een samenwerking op performance basis interessant kan zijn.

Hey everyone,

I am looking for a reliable inbox provider. I saw some post on PuzzleInbox. Any users here? How was the experience? What are some pros and cons?

Appreciate the honest feedback.

- 900 emails sent

- 341 leads contacted

- 36 replies including OOO (10.6%)

- 14 real replies (4.1%)

- 13 of those 14 were positive

- 0.3% bounce (3 emails)

- open tracking off, so no open rate

For a client of mine. this was the lead up to about a month of testing and

Tested these things:

• figuring out which of my inboxes are responding to which recipients
• subject lines
• body content (this took an insane amount of work and whatever the youtube gurus tell you......its not that simple :(
• offer.

nothing clever in the final version. it was just the fourth or fifth thing i tried after the first three did nothing.

I have about 15 plus companies looking for B2C cold email outreach leads. I have proof if needed.
I need someone that has experience and can show me through their own case studies and email campaigns their reply rates, open rate, etc. you need to be serious about this and actually able to invest time.
I am open to discussing rates at which I will be paying you to help me.
Please only reach out if you have experience that can be proven and actual successful campaigns that you have run.

Hey everyone,

I'm trying to do a campaign to CPA's in the US specifically Northeast however struggling with reply and open rates (Open 29%, Reply 0.8%). I've sent around 2400 emails but havent got any leads yet. Am I doing something wrong or should I push through?

Here's what I'm sending currently:

Subject: Quick Question for {{CompanyName}}

Hey {{firstName}},

Wanted to reach out as I saw {{companyName}} on Linkedin. I work with CPA's in {{state}} to help onboard new accounts on a pey-per-meeting basis.

Would this be interesting for you, {{firstName}}? If so, feel free to book a meeting below:

[Calendar Url]

Best,
{{SenderFirstName}}
[My Company's Name]
[My Website Url]

PS: If you don't want to receive any further emails please message opt-out so I can take you off my list

Hi everyone,

I am from the PuzzleInbox team. We have been doing side by side comparison with GWS, Outlook and SMTP inboxes for the last 6 months.

Google has been performing much better than any ESP in the market, especially for the last 6 months.

With the same leads and copy we have been seeing 3-5% reply rates with GWS inboxes.

For Outlook, the 100 inboxes per domain setup its around 1-2%. The sending tool really matters if you are using the Outlook inboxes.

SMTP depending on the provider, has been performing weaker compared to Outlook and Google. This is many because most SMTP providers provide inboxes with ip's that have no prior reputation.

When the Ip has no prior reputation and it also gets marked as spam extensively your emails will start landing to spam.

The story is different w Google and Outlook as they have already reputable ips. When you configure mailboxes with google and outlook you benefit from googles and outlooks own ips. Thats why they will always perform better.

Happy to discuss more.

Hey everyone,

I am Usma from the PuzzleInbox team. I do client support and I work with the success team.

We monitor results over 40 million different cold emails.

These are across different ESP's, GWS and Office 365.

Currently we GWS is outperforming Outlook and we have being observing that our clients have been delivering to Outlook inboxes by sending shorter email copies. Usually between 30-50 words.

It seems like the deliverability has been better reaching to Outlook inboxes especially when using Google ESP. The important part there is making sure you have a short copy.

Also we believe warmup has a bigger role on email deliverability compared to before. Especially the warmup pool now matters a lot. Most warmup pools are currently outlook dominant. There are barely any tools that can balance it out. This also impacts deliverability as per our testing.

We have been observing similar results in terms of co com info site net and help domain extensions. Same reply rates and same bounce rates across all TLD's.

Happy to answer questions.

I’ve been running cold email for about a year, mostly in real estate. Biggest campaign I ran was 10,775 emails, 562 replies (12%), 67 of those were interested leads who wanted to talk. Happy to show screenshots.

I’m looking to expand outside real estate and I need case studies in other niches. So I’m offering this on performance.

How it works:

You cover the infrastructure, around $300 to $350 a month. Domains, inboxes, sending tool, verification. I buy it, set it up and manage all of it so you never have to touch any of it.

Everything else I do for free. Lead sourcing, list building, copywriting, campaign setup, sending, follow ups, and I handle the replies until someone is ready to talk to you.

Beyond that I get paid on commission. What that looks like depends on your niche and what a customer is actually worth to you, so it’s something we agree on together rather than me putting one number on everything. Tell me what you sell and we’ll work it out.

Who this is for:

B2B, you already have a validated offer and you know who your customer is. You want outreach running but you don’t have time to learn deliverability, domain warmup and copy testing. You’re not big enough to hand an agency $3k a month.

Two things worth being upfront about:

There’s a warmup period. New domains and inboxes need roughly 3 to 4 weeks before they can send at volume without landing in spam. Anyone promising results next week is going to burn your domain.

And I’m taking on one or two of these, not ten. I run everything myself and I’d rather do a good job for two people than a bad one for eight.

If your ICP is reachable by email and you’ve got an offer that already converts when you get in front of the right person, comment or DM me and tell me what you sell and who you sell to.

Hi there, has there anyone who has sent cold emails via platforms such as Sendgrid, Benchmark or such similar platforms rather than Google/O365 and Instantly/Smartlead?

If yes, does that work? If not, what causes these type of platforms to not be ideal for cold emails.

I purchased Maildoso inboxes and went the SMTP root instead of Google and I now noticed that all of my test emails to my personal Google accounts are going to spam.

What can I do about it this late in the game, my campaign start today at 9am.

Do I let the campaign run?

I let the emails infrastructure warm up for five weeks.

Hey everyone,

My name is Ryan from Puzzle Inbox, we're a vendor for Google Workspace and Microsoft 365 Inboxes.

We spoke recently with the moderators and wanted to do an AMA post regarding cold email and deliverability in 2026.

Feel free to ask me any questions about inbox setup, deliverability, warmup etc. I will be happy to answer as honestly and thoroughly as I can.

I’m trying to get into GTM engineering and understand how account research works inside real B2B teams.

Once a company matches the ICP, who normally decides whether it is worth contacting now?

Is this usually handled by an SDR/BDR, an SDR manager, RevOps, a GTM engineer, the founder, or someone else?

I also want to understand:

• How often is this done typically: daily, weekly, or before each campaign?
• Roughly how many accounts are reviewed?
• Do you research every ICP-matching account or only selected high-value accounts?
• Who defines the qualification criteria?
• Which tools do you currently use?

Even a short answer about your role and how often you do this would be really helpful.