SMTP and Floating IPs

Posted October 13, 2020 1.1k views

This page on floating IPs, and others like it, explicitly say “Floating IPs do not support SMTP traffic”. The only reason I use a floating IP is for SMTP. Consider, we get a droplet from DO that has already been abused by a previous client who setup a mail server for spam. The IP is on a blacklist and we need to go around begging the listkeepers to remove the IP address. Now we have a clean IP and run for some period of time without issues. Then let’s say the droplet dies and we need to replace it. If we need to get a new IP then we may need to repeat the pain of getting off of lists. But if the mail server is run on a floating IP we can re-use that same IP and there’s no related grief!

So, is there a way to prove to DO that I’m not a bad actor so that I can run SMTP on a floating IP? I have a valid mail server already in use. No black marks on my domains. I just want to port from a competitor DO, do this dance with a DO IP just once, and then have that small peace of mind if things go south.

And yes, all of this is based on experience, not conjecture. Thanks!

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We usually do not recommend running your own mail server and recommend to utilize mail relay services such as SendGrid or MailChimp. This article could provide some insights on why we say that:

With respect to restriction on SMTP traffic over floating IP - this limitation is with implementation and this could not be altered at this time even though you prove that you don’t spam. We are sorry for this limitation.

by Mitchell Anicas
When setting up a web site or application under your own domain, it is likely that you will also want a mail server to handle the domain's incoming and outgoing email. While it is possible to run your own mail server, it is often not the best option for a variety of reasons. This guide will cover many of the reasons that you may not want to run your own mail server, and offer a few alternatives.
  • Commercial services base their pricing on a monthly/yearly fee, per domain, for some limited number of accounts of 1-5. Beyond that the per-account costs are significant. The cost for basic paid email services for a number of domains and just a small number of accounts quickly becomes very prohibitive. It’s simply not scalable. For example, if one person is “admin” for 30 domains, that’s 30 paid users with these services, just for email addresses. For what they want for 5 accounts for 1 domain, I can get a single droplet and host all of my domains with any number of accounts and aliases.

    With paid services we are also subject to their filters, their AV, their browser client, and their configuration details. We are also subject to their outtages due to random spam accounts, and the occasional class C block by RBLs who are tired of lax membership rules by the providers.

    Many paid services do not offer an API for email account maintenance, of course due to abuse by spammers. I am Not a spammer. I value the ability to use scripts to create a number of default accounts for a domain, just like I value the ability to use scripts to spin up and configure servers.

    Given 20 years of consistent reaffirmation of these issues, I DO host my own email, fully aware of the concerns, and despite recommendations and articles about what I may or may not want to do.

    So I am far beyond thinking about the challenge. I already have servers that I’d like to port from a competitor. This one policy is stopping that initiative. It’s not that I just want it all my way. I have experience with fixed IPs and with email service providers that I do not want to repeat. Anyone here who appreciates the value of a floating IP for a web server recognizes the issue which applies even more to a mail server.

    All of that said, I understand that DO has a hard-set restriction against SMTP on a floating IP. I’ll have to host email and probably other servers elsewhere. Thanks anyway.