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> PS: Some old firewalls block dynamic IPs for mail delivery. I'm not sure how common this is today, especially as SPAM and botnets have evolved a lot. The pro

> PS: Some old firewalls block dynamic IPs for mail delivery. I'm not sure how common this is today, especially as SPAM and botnets have evolved a lot. The problem is not that firewalls block dynamic IPs, but that a lot of mail servers, to deal with spam servers, started accepting mail only from some trusted smarthosts. So there might be some server that will reject your mails. (I don't honestly know how much SPF makes things better.) However, your ISP SMTP server will accept mail from its IP range (as they know how to find you if you abuse the service) and will relay mail for you. So probably your best bet is setup outgoing mail to go through it (Internet site with Smarthost, or something like that). Ah, and don't forget to setup your server for SSL!

mindslight 13y ago
Most ISPs block outbound tcp port 25, which is why you'll likely need to setup your ISP's smtp server as a smarthost for a consumer connection. FWIW running a personal mail server on Linode for 8 years, I've never had a remote mail server refuse acceptance due to my IP address not being on some protocartel whitelist. I have had a few annoying false positives from Mailavenger, but clearly that's not my config that's broken :>
- josho 13y ago
  s/most/some/ If an ISP blocks port 25 then it means they'll have a bunch of support calls from people who's email client doesn't send email because SMTP is blocked. So, in my experience not many ISPs do that anymore. Besides it isn't actually an effective way to stop spam.
  - mindslight 13y ago
    Well I currently see both Sonic.net and Verizon blocking outbound tcp/25, which is the extent of my limited sample. According to RFC4409, mail submission is supposed to be done on tcp/587 these days. And no matter how effective at actually stopping spam in general, I suspect tcp/25 is blocked out of a desire to not end up on IP blacklists due to botnetted customers.
Taeram 13y ago
If you're okay having your outgoing mail go through another hop, something like mailgun.com has a free plan if you send less than 10k emails per month.

mindslight 13y ago

Most ISPs block outbound tcp port 25, which is why you'll likely need to setup your ISP's smtp server as a smarthost for a consumer connection. FWIW running a personal mail server on Linode for 8 years, I've never had a remote mail server refuse acceptance due to my IP address not being on some protocartel whitelist. I have had a few annoying false positives from Mailavenger, but clearly that's not my config that's broken :>

josho 13y ago
s/most/some/ If an ISP blocks port 25 then it means they'll have a bunch of support calls from people who's email client doesn't send email because SMTP is blocked. So, in my experience not many ISPs do that anymore. Besides it isn't actually an effective way to stop spam.
- mindslight 13y ago
  Well I currently see both Sonic.net and Verizon blocking outbound tcp/25, which is the extent of my limited sample. According to RFC4409, mail submission is supposed to be done on tcp/587 these days. And no matter how effective at actually stopping spam in general, I suspect tcp/25 is blocked out of a desire to not end up on IP blacklists due to botnetted customers.

Taeram 13y ago

If you're okay having your outgoing mail go through another hop, something like mailgun.com has a free plan if you send less than 10k emails per month.