I'm curious about how people are managing their SMTP relay setups when they have a mix of on-premises devices like MFPs, scanners, and various IoT devices that rely on SMTP, especially when these devices often lack support for encryption or authentication. Specifically, I'm looking for solutions that effectively allow these devices to send email to an Office 365 tenant. Additionally, I've been contemplating the idea of having on-prem equipment that can channel these emails through an Exchange server or any other suitable relay service into the Office 365 infrastructure. What methods or services are you all using?
5 Answers
I built a couple of Postfix SMTP servers behind a load balancer, and they work well with Office 365. Just remember to meet security expectations; it can get tricky depending on your company policies.
Make sure you whitelist them as safe in your Office 365 settings!
We set up IIS SMTP relay on a Windows Server 2019, and it’s locked down as tight as possible. It’s worked well for us, but I'm worried about basic SMTP auth issues coming up soon.
Yeah, I've had a tough time getting IIS SMTP to work right—messages sometimes get stuck.
It’s pretty straightforward to set up under Windows Server, but having a fallback plan is wise since it may not last much longer.
We're still running an on-prem Exchange server that we use for SMTP relay, but we’re considering our options for 2029. My instinct is to transition to a Linux VM with Postfix in the future.
I feel you; I'm still on Exchange 2016 for relaying. It’s becoming a hassle, especially with the upcoming support deadlines—better start planning soon!
What do you mean by planning for 2029? That seems far off, doesn't it?
For our MFPs and scanners, they only need to send to internal emails, so we set them to direct-send to our Exchange Online SMTP endpoint. For everything else, we either use Azure Communication Services or Exchange Online HVE.
I thought Microsoft was enforcing OAuth for all SMTP now, how does that impact your setup?
I've had great success using SMTP2GO for our relay needs. It's got solid features and reporting capabilities, making it easier to manage our email flow. I recommend ensuring you add SMTP2GO to your DNS SPF records for smooth operation.
We use SMTP2GO for most customers without any issues. Just don't forget to configure those SPF records!
Is SMTP2GO a reliable option for an on-prem setup?
I've been using Postfix with a couple of 365 accounts for devices. It has been solid so far.