Best SMTP Services for Microsoft 365

Compare the Top SMTP Services that integrate with Microsoft 365 as of November 2025

This a list of SMTP services that integrate with Microsoft 365. Use the filters on the left to add additional filters for products that have integrations with Microsoft 365. View the products that work with Microsoft 365 in the table below.

What are SMTP Services for Microsoft 365?

SMTP services and SMTP relay services enable organizations to send emails, including bulk emails to customers and users from their website. SMTP service providers provide an SMTP server that can be hosted or used on-premise so websites can send emails and ensure high deliverability of emails and mass email campaigns. Mail transfer agent (MTA) services are part of SMTP services. Compare and read user reviews of the best SMTP services for Microsoft 365 currently available using the table below. This list is updated regularly.

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    OutboundSMTP

    OutboundSMTP

    OutboundSMTP

    DKIM Signing improves the inbox placement of mailbox providers like Gmail, Office365. Multiple Servers in the USA and Europe for increased reliability. No more headaches of managing and maintaining your own email server and IP reputation. Create SPF and DKIM records for your domain names, no prior experience required. If you are suffering from an IP blacklisting our SMTP relay service can solve your reputation problems. 24×7 technical support via phone, chat or email. We are here to ensure your mail gets delivered. you’ll be able to deliver your mail reliably to the inbox. We optimize our sending routes and closely monitor our IP reputations to ensure you the best possible service. We have a Zero Spam Policy that allows us to block or restrict messages that would damage our reliability or the reputation of our customers. You may send from an unlimited number of “From” addresses or domains after you have verified your domain ownership via DNS.
    Starting Price: $4 per 2,500 messages
  • 2
    WP Mail SMTP

    WP Mail SMTP

    WP Mail SMTP

    If you're having issues with WordPress not sending emails, you're not alone. With the rise of aggressive spam filtering, it's tough to reach the inbox unless your emails are configured correctly. Once you've switched from the default WordPress email settings over to WP Mail SMTP, your email deliverability issues will be solved for good. Are you missing out on leads and sales because emails sent from your WordPress site are ending up in the spam folder? Missing out on these opportunities can be a big hit to your bottom line. When your emails are properly authenticated using SMTP, they'll be recognized as legitimate and bypass those aggressive spam filters. WP Mail SMTP integrates with all of the best secure SMTP providers. No matter how many emails you need to send, you can connect with the right provider for your business needs and budget.
    Starting Price: $49 per year
  • 3
    DuoCircle

    DuoCircle

    DuoCircle

    Reliable and secure email hosting services for SMB and Enterprise. Safely processing over 100 million emails per month for our customers. Enhanced gateway security and filtering, inbound email security, email service backup and outbound SMTP using a new high quality infrastructure for top quality results that our customers deserve. Products include, Secure email gateway, email backup MX, email forwarding, outbound SMTP and more. DuoCircle protects against phishing attack with Link Click Protection, a part of the Advanced Threat Defense Suite. You’re covered with Link Click Protection even if site content changes between clicks. You get total protection from phishing and your confidential corporate information is secured because your employees are simply prevented from visiting sites that misuse such information. You get instant feedback in the form of an alert when a suspicious link is about to be visited.
  • 4
    Postmastery

    Postmastery

    Postmastery

    Postmastery provides a platform for professional email monitoring that goes far beyond the obvious ‘click & open’ statistics. Postmastery’s Delivery Analytics platform processes SMTP delivery data from both on-premises mail servers and SMTP providers. It reads data from Microsoft SNDS, Return Path Sender Score and relevant blacklists. Users have access to real time dashboards and receive automatic alerts. High bounce rates, increased delivery times, junk foldering or blacklisting are serious problems in email marketing and they impact your business. Since they affect your reputation , it's best to stay ahead of them. Postmastery offers a baseline for improvement and carries out an email delivery assessment. And, if needed, our specialists provide hands-on support at infrastructure level as well. Focus on your core business and outsource your delivery monitoring to Postmastery. Email delivery experience, expertise and tooling is at your disposal via our 'email delivery control centre'.
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