Email Service FAQ Email Service FAQ


FAQ What types of email service do you provide?

We provide 5 different kinds of email service : Email Backup, Email Forward, Email Store/Forward, Full Service Email and SMTP Outbound Relay (Smarthost). Email Backup, Email Forward, Email Store/Forward and SMTP outbound relay cost $9.99/year, and Full Service Email $19.99/year.

FAQ My email server occasionally goes down and I am worried that I might lose emails during the downtime, which email service should I use?

You may choose Email Backup . After your ETRN host and port are set up in the control panel, our email server will receive emails for you and keep trying to forward email to your backup email server every 10 minutes (this retry interval can be set by you). This way your emails can never be lost.

FAQ Does your email service provide spam filtering?

Yes, all emails coming into our network are scanned for viruses. Many users sign up for our email service just for filtering spams.

FAQ What are IMAP, POP3 and SMTP?

SMTP, POP3 and IMAP are TCP/IP protocols used for mail delivery. Each protocol is a specific set of communication rules between computers.

SMTP(Simple Mail Transfer Protocol) is used when email is delivered from an email client(e.g. Outlook) to an email server or when email is delivered from one email server to another. SMTP uses port 25.

POP3 (Post Office Protocol) allows an email client to download an email from an email server. The POP3 protocol is simple and does not offer many features except for download. Its design assumes that the email client downloads all available email from the server, deletes them from the server and then disconnects. POP3 normally uses port 110. If you want to check your email using several email clients, POP3 is not advised.

IMAP (Internet Message Access Protocol) shares many similar features with POP3. It is also a protocol that an email client can use to download email from an email server. However, IMAP protocol is designed to let users keep their email on the server. IMAP requires more disk space on the server and more CPU resources than POP3, as all emails are stored on the server. IMAP normally uses port 143.

FAQ How does POP3, IMAP, SMTP protocols work?

Suppose you use Dynu mail server as your email server to send an email to You send email from your email client (Apple Mail), and Apple Mail delivers the email to Dynu mail server using SMTP protocol. Dynu mail server delivers the email to Outlook's mail server, using SMTP. John's email client (Thunderbird) downloads the email from to his computer using the POP3 protocol (or IMAP).

FAQ Do you offer a trial period for your email service?

No. We do not offer a trial period for email services as they are often abused. You may request a full refund within 14 days of the purchase if the service is not to your satisfaction.

FAQ What IP ranges should I whitelist to allow delivery of emails from your server to mine?

Email Backup

FAQ What is Email Backup?

Email Backup is a mail queueing system. Our server accepts email destined for your domain. We will hold all emails for you if we cannot deliver it to your mail server(offline due to maintenance or internet downtime). When your mail server comes back online, the emails will be dequeued from our system and delivered to you. We also perform SPAM filtering on Email Backup service.

FAQ My email server went down and now has just come back online, how long does it take to receive the emails queued in your server?

Our mail servers run on a schedule where they will attempt to deliver your email at the next scheduled interval. This interval is normally 10 minutes. You can also set it to a longer a shorter interval. If your email server has already come online and your emails are queued on our server, you may request our email servers to resend the emails immediately. All this can be done via the control panel.

FAQ I do not have Email Backup service, what happens to the emails when the email server is down?

There are 2 categories of e-mails based on their direction of flow: Incoming and Outgoing. In both directions to avoid the problems due to downtime of any server, there is a retry interval which can be from few minutes or an hour or so depeding on how the server is configured . There is also maximum retry duration which is normally 12-24 hours and if after that time sending server is unable to send the e-mail, it sends the sender an undeliverable report.

If you are the sender of the e-mail
If you do not receive an undeliverable report, it means the message is not lost and you do not need to resend the message.

If you are the receiver of the e-mail
In case you have not received an e-mail that you are supposed to receive, you might receive it with a delay or if the maximum retry duration has already expired and the sender has got the undeliverable report, sender is supposed to send you the e-mail again.

FAQ I am using your Email Backup. What MX records should I use ?

You may use with priority 10 and with priority 20 as MX records so that when your mail server is unaccessible, our mail servers will receive your mails for you.

FAQ What IP ranges should I whitelist to allow delivery of emails from your server to mine?

Email Forward

FAQ What can I use Email Forward service for?

With Email Forward service, you can accept and forward mail without needing to run your own mail server. For Example, you run a small business and own a domain name, you would like to receive emails for,, After signing up for Email Forward for your domain name, all you need to do is provide a catch-all email address that will receive all the emails sent to ** accounts.

FAQ Can I send out emails from ** using your Email Forward service?

Email Forward service is only to receive emails for you. If you want to send out emails from ** and manage a list of email accounts, you should sign up for Full Service Email.

FAQ What MX records should I use to use your Email Forward service?

You must use and as your primary mail servers so that all the emails destined for will be received by our mail servers and forwarded to you.

Email Store/Forward

FAQ I host my own email server, but am not able to receive emails on port 25, what service should I use

You should use email store/forward service to receive emails on a port other than port 25.

FAQ I want a relay server to act as smart host for my MS Exchange server, can I use email store/forward service?

No, email store/forward service will only help you receive emails on an alternative ports. To send out emails uing our relay server, you should use SMTP outbound relay service.

FAQ What IP ranges should I whitelist to allow delivery of emails from your server to mine?

SMTP Outbound Relay

FAQ I have purchased SMTP outbound relay service, what should my settings be?

Relay server:
Password: default password is your Dynu account password. You may also change it in the control panel.

FAQ Do you offer a trial account for SMTP outbound relay service?

Due to possible abuse of the trial account, we do not offer free trial accounts. Plus our SMTP outbound relay service works! If you find the service unsatisfactory and you did not abuse the service, we can provide a full refund within 14 days of your purchase.

FAQ Can I send bulk marketing/sales emails using outbound relay service?

No. We apologize but we do not allow bulk marketing/sales emails for our email services to protect our IP reputation.

FAQ What is your relay limit?

SMTP outbound relay allows you to send emails through our servers. To prevent spam, we limit our email accounts to 200 SMTP relays per day which let you send 200 emails from your email address on a daily basis. Your account will be temporarily disabled if it exceeds the limit. The limit applies to the whole domain name. You can upgrade your account to increase this limit at any time by opening a support ticket. The ugrade cost is $4.99/year per additional 200 emails. For example, if your estimate outbound volume is 600 every day. The yearly cost would be $9.99+$4.99*2=$19.97.

FAQ What SPF records to use to include mail relay IPs?

If your domain name already has an SPF record, you need to include the following string to your existing record:

For example, your SPF record may look like v=spf1 ~all. You may use our SPF record generator to generate your SPF record. To check the current SPF reocrd for your domain name, you may use this.

FAQ Some of the emails I relayed using your email servers go into SPAM folder.

There are many possible reasons why an email is marked as SPAM. Our service could be abused but we maintain a list of usable IPs and switch to the new IP address if blacklisted. To prevent the emails going into the SPAM folder, you need to make sure that you include include: in your SPF record

FAQ What configurations need to be done on my email client or email server to use SMTP outbound relay?

You will be provided with login to our SMTP server after you sign up for the service. You may do the following to set up your email server or client:

1. Use as outgoing SMTP server 2. Enable 'Outgoing SMTP server requires authentication' 3. Use the login username and password

If your ISP blocks outbound SMTP port 25, you may use port 2525, 26, 587 or 465 instead.

FAQ I'd like to use SMTP relay for 3 domains and my server only allows one relay username and password. What should I do?

If you have a subscription for one domain name for $9.99/year, the SMTP outbound relay service will only allow you to send out emails for one domain name. If you have subscriptions for multiple domains in your account, you can use one single set of credentials to send out emails for all the domain names. You only need to sign up for SMTP relay for all 3 domains in our system and use any of the 3 relay username and password to configure your server.

Full Service Email

FAQ Why should I use a domain-based email addresses(e.g.

A domain-based email address, like, gives you a more professional appearancewith customers and promotes your website and company. According to a marketing survey, customers are 9 times more likely to choose a company with a professional email address. Owning a domain based email address means you are putting your company in front of your customers every time you send out an email. Customers will be drawn to your website.

With our Full Service Email, it is as simple as signing up with your domain name. You can create unlimited email accounts such as,, etc.

FAQ I have more than 1 domain names. Do I need a full service email for each domain ?

Yes. The mail services are domain based and one service is needed for each domain that you intend to use it with. For example, if you have and and need receive and send emails for both of them, you would have to sign up for Full Service Email for each one of the domains.

FAQ I use your Full Service Email, how do I configure my email client for **

You may refer to email client configuration tutorials. All common email clients such as Thunderbird, Apple Mail, Outlook are included.

FAQ What are the Mx records that I need to set up?

Log into your Dynu Control Panel and navigate to each of your full service email to obtain the details. Note that the MX records and server names will be different for different domains, so please refer to the control panel for each domain's settings.

FAQ I am setting up my email account in a mail client but keep getting errors. Why?

Apart from ensuring the correct IMAP and SMTP server details (available in the control panel for each domain), please also check all the email users and email clients in your internal network to make sure that the correct username and passwords are entered. If a wrong login is attempted for more than 10 times in an hour, the IP address where the connection is from will be banned for a period of an hour. All users from the same IP will no longer be able to connect during that period. We are unable to whitelist any IP addresses for a given domain. In some cases, users have a mail client configured with the wrong password and forget about it. The mail client will keep sending the wrong credentials which causes the IP address to be banned.