Wondering what the benefits are from switching from our own SMTP server to an SMTP service.

They all seem to talk about handling the deliverability issues. However our server is set up with reverse DNS, SPF records, DomainKeys, DKIM and SenderID. We've not yet heard about deliverability issues with our own server. Additionally SenderScore is reporting 99/100.

So why use an SMTP service?

PS: we'll be wishing to send a larger than normal marketing email so this would increase the volume of email from our server in a relatively short period of time

  • What type of volume are you increasing to? With email delivery, you have to worry about ISP relations, infrastructure, maintaining the infrastructure, personnel, etc.
    – user7171
    Apr 28, 2011 at 21:33

4 Answers 4


Key Advantages of a Third Party Mail Sending Solution:

  • Onus of deliverability falls on them; no having to figure out issues by yourself
  • Have the infrastructure to be able to handle larger marketing initiatives and dedicated IPs to build your reputation with
  • Can buy as necessary; don't need it after three months? No problem, you can close up your account and be done until you need it again
  • Reporting and metrics; when you need to find out how many were successfully sent, how many bounced back, how many were opened, how many clicks you received, etc

Disadvantages of a Third Party Mail Sending Solution:

  • Not all of them support marketing campaigns or bulk emails
  • Costs money

However, I will say that the costs of a third party provider are not that bad - especially when you compare them to having to build and maintain your own solution. (Remember that your time is a cost as well!)

If you are looking for just the reporting aspect, you should check out PostageApp, it can be built into your existing SMTP infrastructure so you can achieve a better level of control with the emails you are sending out.

(Full Disclosure: I am the Product Manager of PostageApp.)

  • Thanks for answering. Thing is it's not difficult to set up SPF/DKIM/etc when its all configurable in the mail server. What concerns me is I've tried similar services to PostageApp and a couple test emails were flagged as possible spam when emails from our SMTP server were fine. So it took more of my time to alert the provider and even then there's not much they can do since its a corporate exchange account and they will have no idea what spam rules they're using.
    – Marcus
    Apr 13, 2011 at 20:42
  • Understood. At the current version of PostageApp, we actually only help with designing, sending, and managing the emails through your SMTP server. So if you're happy with your current set up, we have a great layer to place on top to help with design + reporting. Good luck!
    – JonLim
    Apr 14, 2011 at 18:44
  • It costs money is not really a disadvantage. What people often don't realize: managing your own systems costs money too. Just cause a dedicated server might be cheaper to pipe out 1000's of emails a month, it doesn't mean that the cost of the server is the only cost there is. TOC usually includes a lot more.
    – Till
    Sep 17, 2011 at 16:07
  • @Till: I agree completely, I'm not saying it's a true disadvantage (compared to having to run your own server) but it's a disadvantage many people still recognize.
    – JonLim
    Sep 19, 2011 at 15:30

First, congratulations for setting up your own server with SPF, DomainKeys, DKIM, and SenderID. Obviously you care about deliverability!

In this scenario, Postmark is not actually a viable option, simply because we deal specifically with transactional email (welcome emails, invoices and receipts, in-app notifications, etc.) where deliverability failure can lead to significant loss of sales, vs. "bulk" email like a marketing campaign where deliverability failure leads to potential opportunity cost, but not at the same level of severity.

It's possible that a sudden surge in email volume will trip the circuits on ISPs' radars, especially for a marketing campaign, so I would advise that you put some thought into the email itself to avoid an uptick in spam complaints that will damage your sending IP.

You can also consider throttling the campaign or sending it in stages rather than push it out as fast as possible, if that's an option for you.

Also, remember that SenderScore works like a credit rating; in many cases, sending low volumes of email is a lot like having "no credit history". A sudden spike may be over your threshold based on the email volumes you have sent in the past.

That said, the email safeguards you have already taken to verify your identity go a long way in the ISPs eyes, so keep that up, use best practices in your email design, send with some light throttling, and you should be okay.

ESPs (email service providers) like Newsberry or MailChimp are still good options for marketing campaigns if you want to use IP addressess that are specifically used for bulk email and actively monitored to keep their reputation high. This is the equivalent of sending through an IP that has already sent millions of similar emails, vs. one that is normally low volume. Plus you get click tracking statistics to improve your performance, etc.


Like with most things, it is partly science and partly art. You have done a nice job handling the “science” piece of sending emails by implementing proper best practices from server config to a general reputation measurement. The other side of the coin is the “art” of improving your sending performance per ISP along with the probability of inbox delivery. This is an intentionally dynamic landscape comprised of filters, ISP discretion, thresholds and unpredictable user behavior (designating you as spam). It requires constant monitoring comprised of tools, people and actions.

Customers of our SMTP service come to us because they don’t have the expertise and/or resources to allocate. For example, you can set up FBLs with each ISP, but you need someone to monitor, interpret complaints and react with a remedy. Or, you send out a marketing email and AOL blocks your IP because they determine the email to be suspect based on any number of factors. Who contacts AOL to unblock your IP. What happens 3 weeks later when it gets blocked again.

So, when you ask what an SMTP service provider does for you, they should be watching your back, providing visibility to your deliveries and advising you on needed actions to maintain a good sender status. If they are simply handling the science or mechanical end, then you will be no better off.

  • 2
    Thanks for the input: we dont send to free providers/ISP mailboxes. Just corporate businesses or public sector businesses who most likely run their own email server - the kind that don't have feedback loops/whitelists. What would an ESP give us for this sort of usage?
    – Marcus
    Apr 14, 2011 at 16:33

We are blocking majority of 3rd-party mailers such as SendGrid because of extremely high volumes of spam.

For example, since blocking the entire SendGrid network few months ago with Linux command:

iptables -I INPUT -s -j DROP;

Attempted SendGrid Connections: 1,227,000 !

Data: 75M

These 1.2 million emails/connections are 100% SPAM, were not solicited and did not have any relation to any transaction. I know this because of the unique nature of our server and email accounts.

As a webmaster, I highly recommend using your own server to send emails if you are a legitimate sender:

  1. You avoid getting mixed up in the crowd of spammers who are using those 3rd party services and using the same IP's that your emails would be going out of.
  2. It's easy.
  3. It's cheaper.

If you are a spammer, then you probably benefit from having your spam relayed by these 3rd party services rather than having your own IP blocked.

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