MailHop Outbound

This guide will help you set up the MailHop® Outbound service.

What is MailHop Outbound?

MailHop Outbound is an outgoing SMTP relay. You can use it to send professional e-mail for your domain without running your own mail server; send secure and reliable mail on-the-go, such as in hotels and conferences; circumvent port blocking by your ISP; and prevent mail rejections from ISPs and other mail provider which reject messages from dynamic IP addresses.

How do I set it up?

Please complete the following steps to get started with the MailHop Outbound service.

1. Create MailHop Outbound

The first step is to create the MailHop Outbound service. MailHop Outbound is sold in blocks of 150 relays (outgoing emails) per day. This allotment resets every night at midnight UTC. For example, if you buy two blocks, you will be able to send up to 300 messages a day. After purchase, please wait fifteen minutes for the service to activate.

2. Configure your mail client or server

You will need to configure your mail client or server to use MailHop Outbound. Here are the basic settings:

Setting Value
Outgoing SMTP Server outbound.mailhop.org
SMTP Port 25 (default), 2525, or 10025
SMTPS (SSL/TLS) 465 (default) or 10465
Username Your DynDNS.com username
Password Your DynDNS.com password
Authentication Type Basic ("Auth", "Login", "Password")
Use SSL/Encryption Yes (recommended)

We also have a number of specific tutorials for many common mail clients and servers.

3. Modify your SPF record

If you use SPF records, make sure to add include:outbound.mailhop.org to your record. You can learn more here.

Troubleshooting

Mail delivery problems can often be difficult to troubleshoot, as there are many points along the way where a message could be delayed, rejected, or even silently dropped without the sender ever knowing a problem occurred. Please check the following entries to see if they describe your problem; if not, you can contact our support team for further help.

When contacting Support, please send the full headers of any delayed or rejected emails (including timestamps and Received: entries) where available, and describe the timeframe of the problem to the nearest hour with timezone.

I'm receiving 451 Temporary Local Error or Sender Verify Failed errors.

These errors usually indicate a problem with your sending address. The most common causes are:

  • Typo in the sending domain (user@doamin.com instead of user@domain.com)
  • Domain's DNS is misconfigured (no A or MX record; MX record points to an IP address or CNAME; SERVFAIL)
  • Domain has expired or is unregistered (user@domain.local)
  • You have not waited fifteen minutes after purchasing the service for it to activate

Double-check your spelling and ensure your domain is resolving properly. A simple typo is almost always the culprit.

It says I've used up all of my relays for the day, but I haven't sent that many.

If you use MailHop Outbound with a mail server, you must make sure that recipient filtering is enabled. Recipient filtering checks the destination address for incoming e-mail against the local user list; if the user does not exist, your server rejects the message immediately with a 550 User Unknown error. However, if your server is not configured to do this, it will accept the mail, then later reject the message by sending a Non-Delivery Report (NDR) to the sender via Outbound. This results in spam quickly burning through your available relays.

To prevent this, please see this article on enabling recipient filtering in Exchange, or check your mail server's documentation for recipient filtering or LDAP configuration. Disabling NDRs entirely will also resolve this issue.

Frequently Asked Questions

Who should use MailHop Outbound? What should it be used for?

MailHop Outbound is most helpful to individuals, small groups (friends, family and colleagues), and small- to medium-sized businesses for personal communications. The service is not intended for the following:

  • Large-scale mailing lists and newsletters
  • Marketing campaigns and advertising
  • Automated responses (e.g. forum post notifications, account confirmations, purchase receipts)
  • Mass mailings of any kind (e.g. "mail blasts")

Most home or small-business users will find the MailHop Outbound service to work just fine for their daily needs. If you do wish to send a newsletter or mailing list, we recommend using opt-in policies, explicit opt-out instructions on each email, and other procedures as required by the US CAN-SPAM Act, our Acceptable Use Policy and general e-mail etiquette.

If you need a mail relaying service for e-mail marketing campaigns, we recommend SendLabs.

What is a relay? How are relays counted?

A relay is a single outgoing message sent through MailHop Outbound. For messages under 10MB, each message counts for one relay. For example, if you send an e-mail to ten people, you use up ten relays. Please see the chart below for messages over 10MB.

What happens when I reach the daily limit?

There are no overage charges with MailHop Outbound. If you reach your daily limit, you will receive an error message about your daily quota having been exceeded. You can purchase additional MailHop Outbound blocks or wait for the counter to reset at midnight UTC.

What is the message size limit?

MailHop Outbound can send messages up to 50MB in size. Messages larger than 10MB count for multiple relays, as described in the following chart:

Message SizeMultiplier
10MB - <20MB2
20MB - <30MB3
30MB - <40MB4
40MB - <50MB5
Exactly 50MB6

How many recipients can I e-mail at the same time?

MailHop Outbound imposes a limit of 100 recipients per message to prevent abuse. If you have a large mailing list, you should break it down into blocks of 100 recipients apiece or configure your server to send to each recipient individually. Please see the above entry on usage for more information.