I'm transitioning our email security away from Mimecast, shifting our MX records to Microsoft, and integrating Abnormal's email security solution. Currently, most of our SMTP relays are directed at internal recipients (like alerts and scans to email), which we can replace with Microsoft's High Volume Email (HVE) service. However, we have one service still relying on Mimecast as an SMTP relay that needs to send emails to external clients. This disqualifies HVE since it doesn't support sending to external domains. I'm considering using SMTP2Go for this purpose but wanted to get your thoughts on the product or any other recommended alternatives. Security is our top priority; we need a dedicated IP, IP whitelisting, MFA for admins (though SMTP2Go lacks SSO with Entra ID, which is a bummer), and proper DNS authentication for outgoing mail. I'm also looking to use a subdomain to protect our main domain's reputation. Any suggestions?
5 Answers
I've had good experiences with SMTP2GO for similar setups, especially with dedicated IPs and subdomains. The deliverability is quite good too. The lack of SSO is a bit of a hassle, but it’s manageable for a single service account. Other options to consider are Postmark and SendGrid—Postmark's deliverability reputation is strong and SendGrid has SSO on their premium tiers if that’s a crucial feature. Just remember to set up DMARC properly and monitor it, I use Suped for that across my clients to catch any issues quickly.
We've been using SMTP2GO for several clients and it has been pretty reliable. There was a brief issue with Microsoft greylisting, but their support team promptly fixed it by rotating IPs. Also, we really like the API integration for templates—super helpful for various tasks. No SSO is a downside, but we rarely log in since we manage everything through documented API keys in a password manager. Overall, it’s been solid for us over the last few years!
Just curious, how much mail are you planning to send? Have you considered using your typical M365 tenant for it?
If you haven't already, consider using Microsoft's High Volume Email (HVE) option. It doesn’t cover all devices, so you might still have to rely on SMTP2Go for those edge cases.
Yeah, we’re using HVE for most internal stuff, but it doesn't allow external sending, so I still need an alternative.
Azure Communication Service might be worth checking out if you're not expecting a lot of bounces. Just know it requires API use and isn’t a typical relay service.
The emails are sent from an external partner app, not our 365 tenant. I'm checking if they can set up an authenticated mailbox but I’m also looking into experiences with SMTP2Go as a backup.