MailHop Relay -- Readme

Internet mail is actually a fairly fragile thing, and incorrect MX records up will result in lost messages. When using MailHop Relay, you must ensure that mx1.mailhop.org is listed as the highest-Preference mail server for the domain, and that mx2.mailhop.org is not the primary mail server.

If mx1.mailhop.org is not listed as the primary mail server, and it receives email, it will deliver this mail to the highest-Preference mail server without processing it (e.g. no spam scanning, DNSBLs, alternate ports, etc.). If mx2.mailhop.org is listed as the primary mail server, it will simply reject the mail back to sender.

MailHop Relay has no limit on the number or volume of messages that it will relay or store for your domain during normal operation. (If a problem occurs that causes a large build-up of queued messages, such as tarpitting, we will contact you regarding the problem to help you resolve the issue.) However, MailHop Relay has a per-message limitation of 10MB. Messages larger than 10MB will be returned to sender with a useful error message.

Once MailHop Relay receives a message and looks up the receiving mail server, the message is processed and sent off. If your mail server is down when we try to send the mail, we queue it and will continue to try to deliver the mail on the assigned port to the assigned mail server. If you later change the relay port or destination server for your Relay service, messages already queued will still be delivered on the original port to the original server.

For example, if your Relay service is set to mail.example.com on port 2525, and you change the settings to use mail.anotherdomain.com on port 587, any queued mail will still be delivered to mail.example.com on port 2525. (New incoming mail will be sent to mail.anotherdomain.com on port 587.) This is why we highly recommend that you always use a hostname instead of an IP address for the relay server, since mail would be queued for that specific IP address instead of a host record that can be updated to a new IP at any time.

At this time, we are unable to re-tag the destination mail server or port for queued mail.

For the first twenty-four hours after the host fails, we will attempt delivery every 15 minutes. For the next four days, we will retry every hour. For the next five days (up to a total of 10 days from the original failure of the host) we will retry every 2 hours. Our mail servers will also automatically retry delivery (and re-start this process) upon host status changes (such as a change to your server's IP address).

Attempted deliveries from postmaster@mailhop.org, when originating from mailhop.org-named servers, are just an indication of recipient verification being performed by our servers. Whenever someone attempts to send a message through our servers to your domain, we will first attempt to contact your server(s) and verify the recipient(s) of the message. This way, we can avoid accepting the message if the recipient(s) are not valid. Don't worry, this is not an attempt to break into your system, it is simply an optimization to save server resources for you and us. Don't worry about your server being down, either - if your server is unavailable, we assume all recipients are valid, and sort out the invalid ones once you come back online, so you won't miss any mail!

MailHop Relay cannot be used in conjunction with third-party spam scanning or mail hosting services, such as Postini. If you need anti-spam services, MailHop Relay includes spam scanning, virus elimination and DNSBLs to help block unwanted mail, making additional third-party spam scanning redundant and unnecessary.