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Best Practices

Guides on ensuring highest deliverability for your campaigns.
By Mo Rassam
‱ 2 articles

How ColdSend ensures deliverability without any warmup?

TL;DR: ColdSend gives you a clean, pre-warmed dedicated IP, so you can skip IP warm-up. - Your domain still starts at neutral. Reputation is earned only when real humans interact positively with your mail. - Therefore start with your best (cleanest, most engaged) segment, send slowly, watch spam/complaint rates, and scale only while metrics stay green. - Microsoft mailboxes are a special case; expect turbulence until you have proven engagement there; consider deferring them in early campaigns. How we do it Well, 'ensures' is a big word but we're close. Deliverability has several dimensions: 1. The quality of the list that you are reaching out to (i.e., verified emails or not, outlook or google etc.) 2. What you actually send, i.e., your copy. If it has spam words or links, no amount of quality infra will save you. 3. The infrastructure, i.e., are the mailboxes warm or not. The first two are not in our control. The last one is. Warmups are needed for 2 reasons: 1. For your sending IP to acquire a good reputation 2. For your domain to have a good reputation And no, you don't need to log into each mailbox, send a few mails to friends, mark them as "important", wait for replies etc., so the account itself looks "real". ISPs do not score the behaviour of individual mailboxes; they score the sending IP, and the domain. The sending IP is what ColdSend solves. We found a workaround in Azure's APIs that allows us to use their enterprise IPs for sending. These IPs are pre-warmed. Each user in ColdSend gets their own IP, so you are safe from the shared IP shenanigans. The domain part is in your control. And it's not warmups that solve it, it's recipient behaviour (opens, clicks, not spam votes, spam complaints) and "ramp-ups". Meaning, you send high-quality emails to high-quality recipients and ramp up your sending volume slowly. For example, send 500 emails in the first week, then 1000 the next, and so on. Ramp volume slowly so you can measure and optimise real engagement early; that engagement is what builds domain reputation. Domain reputation can only be built by following good deliverability practices (clean lists, good quality copy, real human engagement etc.). ColdSend ensures that you don't land in spam due to sending IP issues; however, you can still abuse your domain reputation by being too eager. We advise starting slow .. but you can still start on day 1, instead of waiting for 3 weeks. My ColdSend email landed in junk, why? Because you sent it to an Outlook/Microsoft account. Honestly, we're still figuring that out .. along with the rest of the industry. For now, we recommend clearing Microsoft accounts from your sending lists and wait until we have a solution for those. There's still a chance that you land in primary but don't take chances at the beginning. There are some advanced workarounds you can utilize to make sure leads using microsoft accounts still receive your emails, but that's beyond the scope of this article. Standby for a detailed guide on ColdSend blog.

Last updated on Sep 26, 2025

Are ColdSend inboxes pre-warmed?

What we mean by “inbox” When you create an “inbox” in ColdSend you’re really creating a sender address (john@yourdomain.com). It can send mail, receive replies, and show up inside your ColdSend dashboard — but it is not a traditional mailbox (no SMTP/IMAP passwords, no log-in screen). So
 is it pre-warmed? No, because sender addresses don’t need warming. Gmail, Outlook, etc. score three things: 1. Your domain (do SPF, DKIM, DMARC pass?) 2. Your sending IP (does it have a good reputation?) 3. Recipient behaviour (opens, clicks, spam reports) The local part (john@, sales@, mary@) is never evaluated separately. Creating fifty addresses adds zero reputation benefit until real people start engaging. Why we still say “50 mails max per inbox on day 1” Even though the address itself isn’t scored, the combination of domain + IP + From: header starts with zero engagement history. Mailing a small, high-quality slice first (≈50 recipients) gives Microsoft & Gmail the positive reactions they need to raise the hidden daily quota attached to that header. After 3–5 days of good metrics you can safely increase volume — our ramp slider automates exactly that. What is already warmed Every domain you add gets its own dedicated IP from our pre-warmed Azure enterprise pool. That IP has existing, positive history, so you can begin mailing immediately. How to warm your domain (not the address) - Week 1: mail your most engaged 50–100 leads - Keep complaint rate under 0.2 % - Gradually increase daily volume while engagement stays high ColdSend’s built-in “ramp” slider can automate the daily increase for you. Bottom line You can start sending the same day you create a sender address—just start small, watch the metrics, and scale as real engagement proves your domain deserves inbox placement.

Last updated on Sep 27, 2025