I think the "decent effort" part is the key thing. We had to change our mail routing temporarily earlier in the year (after having sent via Office 365 for multiple years) and keeping on top of emails that were being blocked was a non-trivial amount of effort (and stress) for a period of time.
Unlike the person to you're replying to we had no issues with Google or Microsoft (once we did the requisite things) - it was Yahoo (and the people they provide email for) and then multiple mid-size organisations who used IP based block lists. At one point our mails were being rejected by our local NHS trust, the London Fire Brigade and a mental health agency we make referrals to. None of this was complicated to resolve but it was energy that could have been better used elsewhere.
I'm not usually part of the "let's go cloud without doing any cost-benefit analysis" movement but with email delivery I was happy when we could go back to routing via Office365 again. If a recipient decides to ban Microsoft's IPs that's usually going to be a bigger problem for them than me.
Unlike the person to you're replying to we had no issues with Google or Microsoft (once we did the requisite things) - it was Yahoo (and the people they provide email for) and then multiple mid-size organisations who used IP based block lists. At one point our mails were being rejected by our local NHS trust, the London Fire Brigade and a mental health agency we make referrals to. None of this was complicated to resolve but it was energy that could have been better used elsewhere.
I'm not usually part of the "let's go cloud without doing any cost-benefit analysis" movement but with email delivery I was happy when we could go back to routing via Office365 again. If a recipient decides to ban Microsoft's IPs that's usually going to be a bigger problem for them than me.