Mailreef is a premium SMTP-based mailbox provider built specifically for cold email outreach. Unlike traditional mailbox providers like Google or Outlook, Mailreef offers dedicated IP infrastructure, ensuring your emails are delivered from clean, reputation-safe servers, without shared limits, DNS complications, or onboarding bottlenecks.
When purchased through SmartSenders, Mailreef allows you to scale quickly with pre-configured SMTP accounts, making it ideal for large-scale outreach teams who need fast setup, control, and consistent deliverability.
Domain Cost: $19/year per domain
Mailbox Cost: $3.99/month per mailbox
Minimum Order: 15 domains × 5 mailboxes each = 75 mailboxes total
Each mailbox is hosted on a dedicated Mailreef SMTP server, with all DNS and authentication automatically configured for immediate use.
Follow these steps to buy Mailreef SMTP domains and mailboxes directly through your Smartlead account:
Log in to your Smartlead account.
Go to Email Accounts on your dashboard.
Click SmartSenders in the top-right corner to create your optimized sending infrastructure.
Under Create Your Primary Inbox Optimized Infra, select Mailreef (SMTP) as your preferred provider.
Choose your desired domain name.
Based on availability, you’ll see similar domain options, select the one(s) you want.
Note: If the domain is unavailable, you’ll see an alert screen.
Review your total cost for the chosen domains and click Save and Next.
Under Create Email Accounts, assign sender personas (first name, last name, profile picture).
The system auto-generates mailboxes per domain, you can customize names before purchase.
Add your forwarding domain, then click Review Order.
Click Make Payment and Complete to finalize your purchase.
Once your order is placed, your Mailreef SMTP mailboxes will be delivered within 24–48 hours with all DNS and authentication records automatically configured.
For Mailreef, a 14-day warmup is required before starting campaigns.
After the warmup, each mailbox can safely send up to 20 cold emails and 20 warm emails per day.
Deliverability is strongest when targeting verified business emails, especially small and medium-sized companies.
Avoid sending to “catch-all” or “risky” email addresses and personal inboxes (e.g., @gmail.com, @yahoo.com, @hotmail.com), as these have high bounce rates and frequently trigger spam filters.
Mailreef uses the tracking domain format:tracking.domainname.com
To configure:
Go to Email Accounts → Email Settings → Custom Domain Tracking in Smartlead.
Enter your tracking domain (e.g., tracking.yourdomain.com) — replace with your actual domain.
Click Verify.
Your custom tracking domain is pre-configured and only needs verification.
Using a verified custom tracking domain improves deliverability and reduces spam flagging.
Setting Recommended
Daily Sending Limit | 20 cold + 20 warm emails per mailbox |
Warm-up Duration | 14–30 days (minimum 1:1 warm-to-cold ratio) |
Daily Ramp-up | +2–4 emails/day |
Reply Rate Target | 65–75% |
Gap Between Emails | Minimum 15 minutes |
Keep warm-up running continuously, even after campaigns go live.
Always include unsubscribe links — avoid “reply to opt out.”
Use heavy Spintax or AI personalization to vary your emails.
Send only to B2B domains (avoid Gmail, Yahoo, Hotmail, etc.).
Limit follow-ups — 1 initial + 1–2 follow-ups max.
Verify all email addresses (NeverBounce or similar).
Avoid large organizations like banks, government, or Fortune 500 — their spam filters are stricter.
1. What is Mailreef?
Mailreef is an email provider designed for cold email outreach, being optimized to quickly setup domains and mailboxes so you can get started with outreach campaigns faster, without having to deal with sending limits, DNS, shared IP’s, or time consuming setup processes for multiple mailboxes and sender domains.
2. What is the pricing structure for SMTP accounts by Mailreef on SmartSenders?
SMTP (Mailreef): $19 per domain per year + $3.99 per mailbox per month, with a minimum order of 15 domains and 5 mailboxes per domain (total minimum of 75 mailboxes).
3. What are the differences between Mailreef and Google/Microsoft mailboxes?
The primary difference between Mailreef and Google/Microsoft mailboxes is that Mailreef only provides users with dedicated IP/custom infrastructure to ensure the highest possible success rate for cold email campaigns. Whereas, Google/Microsoft's shared IP addresses group thousands of users who are unfamiliar with one another under a single server, all sharing the same inherited server reputation, so one bad sender can ruin the deliverability of everyone else on that server.
Mailreef gives you complete control over your sending activities, with no artificial restrictions from your email provider.
4. What is the difference between buying Mailreef from Smartlead vs going directly to Mailreef?
The primary difference between purchasing Mailreef through Smartlead and directly from Mailreef is that you are not required to participate in an onboarding call with us in order to access Mailreef's services, and you save approximately $40/month when purchasing Mailreef through Smartlead.
Purchasing Mailreef directly allows you to bring over your own existing domains for outreach, as well as give you more direct control over your sending limits and the ability to gradually ramp up your mailbox count, as opposed to having to buy all 75 mailboxes at once through Smartlead.
5. Do I need to warm up Mailreef mailboxes?
Yes, Mailreef mailboxes are standard SMTP and IMAP mailboxes hosted on brand new dedicated IP addresses with no prior sender history, so their sender reputation must be established prior to launching your outreach campaign to ensure high deliverability.
6. Does Mailreef Accounts have sending limits?
Mailreef mailboxes with Smartlead are limited to 20 cold emails and 20 warm emails per day.
7. Can I use my own domain with Mailreef?
When purchasing Mailreef through Smartlead, you cannot bring over any existing sender domains. By purchasing Mailreef directly, you will be able to transfer an unlimited number of domains to our service or purchase as many fully configured sender domains as you want through their platform.
8. Can I Use Custom Tracking Domains With Mailreef Mailboxes?
Yes you can! Mailreef mailboxes can be configured with a custom tracking domain, and we strongly recommend using them for consistent deliverability.
9. How many emails should I send per day with Mailreef mailboxes?
We suggest you to maintain a low, consistent sending volume with volume spread across multiple mailboxes and domains as opposed to overly loading any single domain/mailbox with sending volumes higher than 20 cold + 20 warm email sends per mailbox, per day.
10. What happens if my server gets burned?
In the rare event that you experience poor deliverability rates due to a burned server infrastructure, Mailreef can replace your server infrastructure.
11. What is the recommended warmup settings?
Warmup every email account and always keep them warming. For every cold email sent, send one warming email - so maintain a 1:1 ratio. You should warm up your domains and mailboxes for a minimum of 14 days before sending any cold email. Warming up for 30+ days is even better!
12. Ideal sending volume for Mailreef accounts?
When a mailbox is fully warmed, you should be doing 20 cold emails and 20 warming emails per day. You should also space these emails out evenly apart - sending high volumes in short bursts typically causes issues regardless of the email provider (Mailreef, Google, Outlook, etc...)
13. Are we assigned dedicated IPs per order?
Mailreef assigns you a dedicated server to your Smartlead order. Please note that you are solely responsible for the reputation of this server - no one else has access to your IP and server. Should anything go awry, we'll review its reputation and determine if a replacement is appropriate. If you need additional servers, please reach out to me and we'll evaluate the possibility of expanding your infrastructure. The lower the volume on the server the better your deliverability will be in theory.
14. Recommended best practices for Mailreef accounts
Unsubscribe Links: Always include unsubscribe links in your emails. Phrases like "reply to opt-out" often lead to more spam reports than a straightforward unsubscribe link. This rule is crucial to follow.
Spintax/AI Content: Spam filters know when you're sending the same email repeatedly - changing only the 'first name' doesn’t count as variation anymore. You need to use heavy spintax or AI driven personalization to introduce as many variations as possible into your email template. Sending identical emails repeatedly will lead to a gradual decrease in open rates; spintax/AI prevents this decline and give you consistently high open rates.
B2B Emails Only: Avoid sending to personal email addresses such as @gmail.com, @yahoo.com, @hotmail.com, @msn.com, etc. Focus on reaching out to professional domains relevant to their respective businesses.
Follow Ups: We suggest sending 1 initial email and then a max of 2 follow up emails. We see that the spam button is hit way more on follow ups and typically lowers your deliverability quickly after a few follow ups to the same unresponsive prospect. For example, at Mailreef we only send 1 initial email and 1 follow up and cut it at that.
Verify Email Address: You should verify all emails before you send. Do not email Catchalls or Risky emails as they will likely bounce. NeverBounce is a great resource for this. It's worth noting that Apollo.io's emails should still be run through a 3rd party verification tool - there tends to be stale data in their platform.
Types Of Companies To Avoid: Generally speaking, emailing Fortune 500 companies, government offices, banks, finance, accounting, and/or hospitals. This isn't just related to Mailreef, but cold email in general. These types of receiving mailboxes have very strict spam filters and will likely spam report your email faster to blacklists than emailing small and medium sized businesses.
