Best Practices for Improving Email Deliverability to Outlook Inbox

·Jul 18, 2025 06:15 AM·

What do people do for deliverability today, especially for getting into Outlook inboxes consistently? My current setup:

Zapmail for Gmail mailboxes + new domains
Warmup in Instantly + Smartlead (in total 15-20 warmup emails/day after rampup) for 2 weeks before use
Send 20 outbound emails + ~20 warmup emails/day/mailbox after 2 weeks

Warmup emails don’t really land in spam for most mailboxes (98%+ reputation on Smartlead + Instantly), but we do land in spam a lot especially when emailing Outlook users, this is obvious when I run a real deliverability test. Really looking to hear what email infra setup others have tried that work. Especially if you run a cold email agency / send a lot of cold emails.

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15 comments

· Sorted by Oldest

Nick R.
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Try to send from g-auite to outlook. Couple of years ago was a rule to do the opposite but we see a better deliverability today if you do that. And also I think two weeks of warm up isn't enough. We warm up 4-8 weeks up to 40 warmup emails a day
Jared R.
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I also use Namit J. for inboxes which have been performing better than zapmail for me
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Vrinda G.
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We simply use smartlead for email warmup + outbound. Sending ~8-10 emails per mailbox with 2 follow up emails. So max sending 24-30 emails per day per inbox. I have noticed that after 15 weeks, open rates start dropping. So now trying to rotate mailboxes + change script completely after every 15 days...
Namit J.
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Happy to have a conversation Xiaohan S. . Aerosend manages your deliverability from creation -> alerting when domains are about to die
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Paris P.
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I also recommend rotating accounts you’re using
Jared R.
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Yes! Paris P. - having multiple domains and inboxes are essential!
Xiaohan S.
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Interesting Paris P. - Like creating a new mailbox on the same domain after a while?
Xiaohan S.
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Namit J. Happy to chat. I tried a few SMTP solutions like Maildoso/Salesforge and they generally have worse deliverability than Gmail / Office 365 from what I see though. Honestly losing my confidence in custom SMTP infra a bit lol
Namit J.
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That’s because setting up Custom SMTP correctly can be challenging. Can discuss backend privately and how to do it right. meetings.hubspot.com/namit4/15-minute-aerosend
Marijan.K
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Hey Namit, just out of curiosity - what is your experience with delivering into microsoft infrastructure?
Namit J.
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It’s tougher than Google but we have had no problems landing into Outlook
Namit J.
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Marijan.K
Marijan.K
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Thanks Namit, I'm intrigued to at least give you guys a shot. Do you have a list of guidelines regarding copy and other tweaks to ensue maximum deliverability per ESP?
Namit J.
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Ofcourse. I give free consultations to all Aerosend customers. Happy to send a voice note right now or once you buy Aerosend we can meet over a call and talk strategy
Marijan.K
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I'll setup a call through the link you shared 🙂 The main idea is to complement the quality of your inboxes and not mess them up with unhealthy copy/setup practices

Best Practices for Improving Email Deliverability to Outlook Inbox | RevGenius

Nick R.
·
·
Try to send from g-auite to outlook. Couple of years ago was a rule to do the opposite but we see a better deliverability today if you do that. And also I think two weeks of warm up isn't enough. We warm up 4-8 weeks up to 40 warmup emails a day
Jared R.
·
·
I also use Namit J. for inboxes which have been performing better than zapmail for me
❤️1
Vrinda G.
·
·
We simply use smartlead for email warmup + outbound. Sending ~8-10 emails per mailbox with 2 follow up emails. So max sending 24-30 emails per day per inbox. I have noticed that after 15 weeks, open rates start dropping. So now trying to rotate mailboxes + change script completely after every 15 days...
Namit J.
·
·
Happy to have a conversation Xiaohan S. . Aerosend manages your deliverability from creation -> alerting when domains are about to die
🙌1
Paris P.
·
·
I also recommend rotating accounts you’re using
Jared R.
·
·
Yes! Paris P. - having multiple domains and inboxes are essential!
Xiaohan S.
·
·
Interesting Paris P. - Like creating a new mailbox on the same domain after a while?
Xiaohan S.
·
·
Namit J. Happy to chat. I tried a few SMTP solutions like Maildoso/Salesforge and they generally have worse deliverability than Gmail / Office 365 from what I see though. Honestly losing my confidence in custom SMTP infra a bit lol
Namit J.
·
·
That’s because setting up Custom SMTP correctly can be challenging. Can discuss backend privately and how to do it right. meetings.hubspot.com/namit4/15-minute-aerosend
Marijan.K
·
·
Hey Namit, just out of curiosity - what is your experience with delivering into microsoft infrastructure?
Namit J.
·
·
It’s tougher than Google but we have had no problems landing into Outlook
Namit J.
·
·
Marijan.K
Marijan.K
·
·
Thanks Namit, I'm intrigued to at least give you guys a shot. Do you have a list of guidelines regarding copy and other tweaks to ensue maximum deliverability per ESP?
Namit J.
·
·
Ofcourse. I give free consultations to all Aerosend customers. Happy to send a voice note right now or once you buy Aerosend we can meet over a call and talk strategy
Marijan.K
·
·
I'll setup a call through the link you shared 🙂 The main idea is to complement the quality of your inboxes and not mess them up with unhealthy copy/setup practices