postfix setup: add some commented-out notes about port-25 workarounds

content/blog/2022-04-05-systemd-nspawn-postfix.md

@@ -303,15 +303,45 @@ Notes:
   *inbound* port 25 is blocked, so i can't *receive* email
 
 VPN?
+  https://tunnelbroker.net/
+    FREE IPv6 tunnel
+    pairs with a free DNS & reverse-DNS service
+    they block output SMTP 25 by default, but will unblock that on case-by-case
+      looks like they block both directions: https://forums.he.net/index.php?topic=3084.0
+    Hurricane Electric operates in the Westin
+      and Fremont, CA :thinking:
+      VERY well-established; Mike Leber
+      organically grown, privately held & against selling equity or exits
+        https://www.telecomramblings.com/2015/06/industry-spotlight-hurricane-electric-ceo-mike-leber/
+  https://en.wikipedia.org/wiki/List_of_IPv6_tunnel_brokers
+    tunnelbroker.se offers wireguard + RDNS + BGP
+    August Internet offers wireguard + RDNS + BGP
+
+  https://hoppy.network/
+    explicitly allows port 25; dedicated and clean IPv4 address, /56 block of IPv6; $8/mo
   https://www.ovpn.com/en/features/public-ipv4
     IPv4 addr -- with PTR -- for $3/mo + $5-7/mo VPN service.
     explicitly mentions email support.
-    allows BTC payments
+    allows BTC payments; claims anonymity in the process; email is OPTIONAL when registering
+    people recommend it for SMTP: https://www.reddit.com/r/homelab/comments/9fo287/comment/e5za2qk/?utm_source=share&utm_medium=web2x&context=3
+    traffic neutral; allows bt/etc: https://www.ovpn.com/en/faq/functionality/does-ovpn-allow-file-sharingp2pbittorrentutorrent
+     4 connections per account
+  purevpn:
+    also allows port-forwarding + static IP for $3.50 above base; claims PTR records
+      https://support.purevpn.com/how-can-i-access-ptr-record-service
+    accepts BTC
+    $2-$11/mo base price
   https://www.perfect-privacy.com
     *maybe* supports explicitly port-forwarding. $10-12/mo.
   Vultr reverse proxy
 
 MX forwarder?
+  https://ghettosmtp.com/
+    receive only, budgeted to 2000 mails/month
+    no outbout SMTP, except FAQ #13 mentions a secret test/beta
+    manual activation, by emailing them & asking access.
+  https://www.dynu.com/Email  ($10/yr forwarder)
+  https://rollernet.us  ($30/yr forwarder; 25MB/day volume)
   https://www.dnsexit.com/Direct.sv?cmd=mailRedirect
     $25/yr; no account limit. requires port 26 or 940
   mailgun
@@ -319,11 +349,26 @@ MX forwarder?
   Mandrill
   SendGrid
   SMTP2Go
-  Amazon SES
-  https://ghettosmtp.com/
-    receive only, budgeted to 2000 mails/month
-    no outbout SMTP, except FAQ #13 mentions a secret test/beta
-    manual activation, by emailing them & asking access.
+  Amazon SES/lambda
+    https://github.com/arithmetric/aws-lambda-ses-forwarder
+    i think Amazon has to store my emails, and then the lambda is invoked to forward it to my MX.
+    unless i have a static IP, i believe this is the case for any way of routing mail.
+
+  gmail:
+    operates a SMTP relay: https://support.google.com/a/answer/176600?hl=en
 
   CenturyLink might allow outbound email via their OWN forwarder?
+  ~~forward via UW? HAK5 pineapple?~~
+
+CenturyLink:
+  https://www.centurylink.com/home/help/internet/email/understanding-port-25-filtering.html
+    require static IP to disable port 25 filtering.
+    can get a static IP as a residential customer
+      costs $5/mo or $10/mo? https://www.centurylink.com/home/help/notices/staticip.html
+        https://www.reddit.com/r/centurylink/comments/ij1f3j/how_much_is_a_static_ip_address/
+  i can reach MX 587 (submission), but not 25:
+    $ nmap -sT lxomp51w.centurylink.com.
+  port 25 shows "filtered"
+    $ nmap -sT -p 25 lxomp51w.centurylink.com.
+
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