Admin Jerry<p>Well, finally, email notifications on hear-me.social are working again. They seemingly broke with the last upgrade and fortunately were also broken on my test instance so I could play around without disrupting services here.</p><p>The cause was bizarre, and it took a while to find it.</p><p>I have my own email server for a hundred reasons, and it's hosted on Digital Ocean. I host this Mastodon server, (and others) on Digital Ocean. But, around the time I did the Mastodon upgrade, the Mastodon servers could no longer send email.</p><p>The cause...</p><p>Digital Ocean has a policy to restrict IPV6 access to an SMTP server hosted on Digital Ocean. Mastodon was attempting to connect to my mail server using IPV6 and was blocked. Oddly, I can connect via IPV6 from my home computer, which is against their policy and from other DO servers. Maybe not for long?</p><p>I found reference to this Digital Ocean policy in a post from 2014, but other hosters probably have the same policy.</p><p>"The main reason behind why we have chosen to block these ports by default is due to how blacklists handle IPv6 addresses, in the event of a spam report. Rather than listing only one address, blacklists will list the full /64 subnet of addresses that the spam report came from, which impacts a whole range of customers and droplets unaffiliated with the incriminating droplet/user. When a whole range is affected, even newly created droplets can be affected if they are assigned an IP for a blacklisted subnet."</p><p>Had I known this, I would have set up the mail server to only use IPV4, but it's a bit late to change it. My workaround was to use the IPV4 address for the SMTP server in the Mastodon configuration file instead of using the domain name.</p><p>Anyway, anyone on hear-me.social who runs into issues with email from this point on, please let me know.</p><p><a href="https://hear-me.social/tags/SelfHosting" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SelfHosting</span></a> <a href="https://hear-me.social/tags/SMTP" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SMTP</span></a> <a href="https://hear-me.social/tags/Email" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Email</span></a> <a href="https://hear-me.social/tags/DigitalOcean" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>DigitalOcean</span></a> <a href="https://hear-me.social/tags/HearMeSocial" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HearMeSocial</span></a></p>