How to Warm Up an IP Address

When first sending emails out on a brand new dedicated IP address or range of IP addresses, it is important to keep in mind best email practices in order to keep your emails out of your recipients’ spam folders, even if you are simply switching email service providers. A brand new IP address will not have any sort of mailing history, so there is no way for ISPs to tell whether a new stream of email traffic is legitimate, or perhaps due to a mail system being compromised. The following guidelines will provide some insight on bolstering the reputation of your IP address (with some SMTP2GO-specific advice included).

Gradually Increasing Sent Mail Volume

Once you’ve checked your SPF record, and considered setting up a custom DKIM signature, you will need to gradually ramp up the number of emails you send out in order to avoid the risk of being blocked.

SMTP2GO pre-warms up dedicated IP addresses to a certain extent. However, if you suddenly send out 100,000 emails from a brand new SMTP2GO high volume (dedicated IP address) account, some ISPs may assume that your mail system has been compromised, and the emails will be blocked. Most ISPs have fail-safes in place that identify mass mailings from unknown IP addresses as spam.

In order to prevent your emails from being flagged, you will need to gradually increase your outbound traffic so as not to trigger the fail-safes. This is a simpler task if you are just starting a new campaign with a relatively small number of contacts, but rather more daunting if you’ve already established many business relationships and have just switched to SMTP2GO. In either case, the solution is similar; the only major difference lies in the numbers.

To ramp up outbound email traffic at an appropriate rate, make an estimate of the number of emails you plan to send out monthly, and then divide that number by 30. (Example: if you plan to send out 100,000 emails in your first month, divide 100,000 by 30, and send out around 3,000 to 4,000 per day, as a rough guide.) This is a slow process, but a steady stream of outbound emails gives a recipient ISP time to properly test the quality and nature of your email traffic, and build up a secret reputation figure for your IP address. Content and domain reputation is also very important, and this is likely to be built up at the same time as your IP reputation.

Alternatively, if you are already sending out a very large number of emails per month and are simply switching to SMTP2GO, you may not want to wait a full month to be able to send out your desired quantity of emails. In this case, it may be better to spend a month phasing your emails from the old ESP to SMTP2GO (thereby warming up the new IP in the process).


One final point that seems obvious but bears repeating is that your results should be monitored constantly. Any spam complaints from your emails can be seen in your SMTP2GO control panel, so you can find out immediately if your recipients are clicking on the ‘Spam’ button for your email in Hotmail, Yahoo, AOL and others. You can also easily see your bounce rate. A high bounce rate can indicate problems with your mailing list, which can lead to bigger problems in the future.

Also worth noting is the fact that Return Path provides a way to view your exact inbox placement rate with most major ISP’s, however to view those statistics you do need to become Return Path certified (which we can help with), and it does cost several thousands of dollars in most cases. A more DIY approach is to create an email address at the major email providers (Gmail, Yahoo, AOL, Outlook/Hotmail) and be sure to always include them in each of your mailings. You can then periodically check them to see if your emails are being placed into the inbox of spam folder in each case.

To get a good overall idea of your current IP address’ reputation, visit (which is operated by Return Path) and search for your IP address. You’ll see a variety of statistics to accurately measure your current standing.  The reading from SenderScore will look something like this:


Warming up your new IP address has a bit of a learning curve, but if you follow the steps provided, you have a much higher chance of successfully getting your messages to the contacts you need to reach.

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March Release & Updates

SMTP2GO’s newest release brings general enhancements and updates to improve the user experience.

  • If you joined or upgraded your SMTP2GO account after June 2013 (and are therefore paying via our new payment processor called Fastspring) you now have the ability to purchase blocks of extra emails. You can do this to temporarily increase your email quota instead of upgrading to a higher plan.
  • The account reputation percentage calculation has now been adjusted to more accurately reflect account behavior. Bounce and spam rate calculations are now more closely aligned with our recommended bounce and spam rates before the reputation percentage is lowered. This will also help to increase account reputation more quickly after a temporary sending issue has been resolved.Account Reputation
  • Adjustments are continually made to our hard/soft bounce classification system, to ensure that it stays as accurate as possible. Simply checking the SMTP response code (e.g. 421, 450, 551, etc.)  does not give a reliable indicator of whether a bounce is hard or soft, as a certain percentage of recipient mail servers (including some very big email providers) do not respond with sensible or relevant response codes. The only reliable way (what we do!) to determine if a bounce is hard or soft is to maintain a large database of known responses given by recipient mail servers, which have been properly classified.
  • Your local currency is now selected by default when subscribing to a new SMTP2GO plan. US dollars can still be selected as an option.
  • The Terms of Service Agreement has been updated to include restrictions on the use of SMTP2GO to handle ‘auto-forwarded’ messages. More information is available here.

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SMTP2GO Ranked in Deloitte Tech Fast 500: 2nd Consecutive Year

We’re continuing to grow, and have been awarded a place in Deloitte’s 2013 Technology Fast 500 list for Asia Pacific for the 2nd consecutive year. Deloitte ranked SMTP2GO the 461st fastest-growing company in Asia Pacific for 2013. Winners for 2013 were selected based on the highest percentage of revenue growth from 2011 to 2013.
We’re aiming for 3 years in a row, so look out for us in 2014!


About Deloitte Technology Fast 500:
The Deloitte Technology Fast 500 is the pre-eminent technology awards program in Asia Pacific with 2013 being its 12th anniversary. Combining technological innovation, entrepreneurship and rapid growth, Fast 500 companies large, small, public, and private are on the cutting edge and are transforming the way we do business. The top 500 companies averaged a revenue growth of 356%, staggering by any measure, though this figure is down from last year’s average growth of 467%.


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How to Get Unblocked From

Emails sent to email addresses can occasionally be blocked. provides a solution to this issue by allowing domains to be added to their list of approved senders. Adding these domains requires proof of ownership. This also applies to other domains controlled by such as and

To do this, create a free account. It is not advised that existing mail accounts, such as Gmail or Yahoo, are used to log in to this service.

register login english and russian

Once the account has been created, go to the postmaster page and enter your domain name. Note: the screenshots below may appear different when you view the site.

add domain step 1

There will be three options for verifying and proving ownership of the domain. Choose one option and follow the instructions provided.

add domain step 2

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How to Effectively Report Spam

Very few people know how to properly report spam. This is a quick guide which outlines the best way of dealing with spam, with the aim of getting the underlying spammers shut down.

The most effective way to deal with a spam email is to report it directly to the organization that is responsible for the spam email’s originating IP address. These organizations will usually respond very quickly to such requests (as they care about their own reputations).

You will firstly need to locate the following information:

  • The email headers of the spam email.
  • The originating IP address of the spam email.
  • A responsible email address(es) for that IP address.

To find out the originating IP address of the spam email, view the spam email’s headers. There are many ways to do this, as every email client is different. Here are some examples:

  • Gmail – On the right hand side of the email message there is a “Reply” button with a small drop down icon beside it. Click the small icon and choose “Show original”.
  • Outlook 2003 - Right-click the email message and select “Options…”
  • Outlook 2007 – Right-click the email message and select “Message Options…”
  • Outlook 2010 and 2013 - In the message window, select the File tab then click the “Properties” button.
  •, and – On the right hand side of the email message there is a drop down box labelled “Actions”. Choose “View message source” from the list.

source example

You will find the IP address in the section labelled “Received: from”. Usually there is more than one of these, so select the last one, which is the earliest. This will be the IP address of the actual computer from which the spam email originated.


Go to the DomainTools website: and put in the IP address we found in the previous step. Click “Lookup”.

Domain Tools 1Look for an “abuse@” email address. If it is not available, look for another email address that seems likely to be checked by someone. This could be labelled “support” or “admin”.


With all this collected information, compose an email. Address it to the responsible email address from the above step, and request that the spam originating from the IP address be stopped. Paste in a copy of the spam email’s headers to finish the message.

Below is an example:

spam complaint email
An alternative to doing this manually is to use the free service provided by SpamCop. This website will analyse the headers and make contact with those responsible for the IP address.

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Inserting unsubscribe links in your emails – new feature

We’ve just released a much requested feature, giving our customers the ability to easily insert an unsubscribe link in the emails that they send. This can be found from the ‘Settings > More > Unsubscribe Options‘ page in your SMTP2GO control panel.

When you send an email newsletter to multiple recipients, your recipients will expect to see a way they can remove themselves from your mailing list, if they so choose. You can now easily insert an unsubscribe link, which will allow a recipient to simply click the link, and be taken to a web-page which will show confirmation that they have been immediately unsubscribed.

This functionality allows you to avoid having to build your own unsubscribe system, or forcing your recipients to have to email you to get removed.

In general, by using the new unsubscribe link functionality, your newsletter emails will appear more professional, and you will receive fewer spam complaints (which are often created in frustration if a recipient cannot easily unsubscribe).


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Deloitte Technology Fast 500 Winner!

SMTP2GO is growing very quickly, and late last year was featured in the Deloitte Technology Fast 500 for Asia/Pacific.

We had the pleasure of meeting New Zealand’s Minister for Communications and Information Technology, Amy Adams in Wellington.

It was an excellent day and a great achievement by our entire team. Congrats!



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New web-based email marketing service

We’re proud to announce the launch of Fluttermail Email Marketing, a really useful web-based service for creating and sending email newsletters to thousands of your contacts.

While SMTP2GO is perfect for sending important transactional and day-to-day emails, and for integrating with email software or apps that need an SMTP server to work, Fluttermail is an “all in one” web app for people who like to do everything within one website. You can compose, send and track emails all from the one website.

We wanted to make Fluttermail different to all its competitors, and one way we’ve done that is pricing, which has really made it affordable to almost all businesses. Check it out!

Fluttermail email marketing service



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An SMTP server for Airlink101 Network Cameras

Airlink101 network cameras require a non-SSL SMTP server in order to send emails.

SMTP2Go’s SMTP server will work with these devices, as the SMTP2Go service can work with or without SSL enabled.

You can test the service with a free trial. Please note that you should try setting the Port Number to each of the following (until you are able to send emails): 2525, 587, 8025, 25.

Thanks to one of our members for advising us about this. An example screenshot (from the SkyIPCam747W Wireless Network Camera) is shown below:

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Hard/soft weekly bounce reporting for Corporate service

SMTP2Go Corporate’s improved weekly bounce reporting service has recently been enabled.

The new weekly reports include only true, hard bounces. A hard bounce is an email address that has proven to be undeliverable, and will never accept email in the future.

The only truly accurate method of determing whether a bounce is hard or soft is to analyse the bounce message for positive/negative keyword phrases.

So… how do we do it?

When an email bounces, we  scan the bounce-back message against hundreds of specific known soft bounce keyword phrases, such as ‘Mailbox is full’, ‘SPF check failed’, and ‘We do not accept junk mail’.
If a bounce’s message includes any of our soft bounce keyword phrases, it is classified as soft.

If the bounce hasn’t already been classified as soft, we then scan the message against hundreds of specific known hard bounce keyword phrases, such as ‘Invalid email recipient’ or ‘The account does not exist’.
If a bounce’s message includes any of our hard bounce keyword phrases (and wasn’t already classified as soft), it is classified as hard.

Our classification system has a very high level of accuracy, and we’re sure it will be of use to anyone using SMTP2Go Corporate to send to mailing lists.

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