External SMTP for Cold Emails – Can It Improve My Deliverability?


This one’s about deliverability. And I’d say it’s for more advanced email senders. I tried to explain things as simply as possible for all readers of the Woodpecker blog to get the idea behind the external SMTP services. Check what external SMTP is, when it’s a good idea to use it, and if you could be interested in using it to send your cold emails.

Ok, so let’s start from the basics.

Usually, when you get about cold emailing, you don’t know very much about SMTP and IMAP. You don’t think about how sending emails work. You just want to hit “Send” and have your emails delivered.

Only a few campaigns later, if you pay attention to your deliverability rates, you might start digging into the email sending details. You may want to set up a separate mailbox on a separate domain exclusively for cold email campaigns.

Check why separate mailbox for cold emails gives you a better control of their deliverability >>

And if you do have a separate mailbox for sending cold email, that’s great. That’s the first step towards full control over your email deliverability.

Using an external SMTP service is another step, which you may want to take for even more control over how your emails get sent and how many of them get delivered.

Don’t get me wrong here: this is not a must. It’s an option you can take in some situations. I’ll describe some examples later on, but first…

How does default SMTP work at major email providers?

As you may already know from my previous post about SMTP & IMAP, SMTP is a protocol that takes care of sending your email messages. Each email service provider (like for instance Google, Outlook, Yahoo) offers you their own SMTP and IMAP services.

So usually, you don’t even think about it. You decide to use Gmail, so you get your SMTP service from Google (it’s just an example here, so don’t take it personally at any times).

In such a case, you could compare Google to a post office. As a post office, Google hires mailmen to allow you to send messages (SMTP) and receive messages (IMAP). You don’t get to choose who the Google’s mailmen are. You don’t know anything about their reputation: if they’re reliable, polite, or liked in their neighbourhood. You just trust Google, as a reputable post office, that they’ve hired reputable mailmen.

But at such a big post office, there are so many mailmen that:

  • Sometimes your messages will be delivered by the best ones friendly, always smiling mailmen, who see every door opening before they even reach for the doorbell.
  • Sometimes your messages may be delivered by neutral mailmen, the ones people don’t know and don’t treat as their friends but merely as mailmen.
  • Or sometimes, your messages may be delivered by mailmen who for some reason have been detested by every dog in the neighbourhood, so they can’t even get to the door to actually deliver your message to its recipient.

Anyway, you can never be sure who will be chosen to deliver your message. It’s random.

Now, in the domain of email, the mailmen are the IPs. If you get assigned an IP with a poor reputation to send a specific batch of emails, your deliverability rate may be lower because of that.

You could try to check the IP reputation before sending, but the problem is, you are not just assigned the IP once. Every once in a while, your email provider assigns you a randomly chosen IP for sending emails. The IP changes. So you can’t have full control over that.

What is the external SMTP service?

Sticking to our post office metaphor, imagine you send your private letters via traditional mail, but you decide to hire another company to deliver exclusively your business messages. In the company, you can hire a private mailman with proven impeccable reputation. This mailman’s job will be to deliver your messages only. He won’t be working for anyone else but you.

In the metaphor, the external mail company you hire to deliver your business correspondence is the external SMTP service provider. And your private mailman is a dedicated IP you may buy to be sure your emails are not only smoothly sent, but also effectively delivered.

So, is the external SMTP for everyone?

I’d say it’s not. And that’s because it is an advanced email configuration that requires:

a) additional advanced configuration of your domain and DNS servers, so if you’re not able to handle that, perhaps it’s not the best solution for you;

b) additional costs of the SMTP service, so you really need a good reason and a specific situation to benefit from it.

If you’re sending classic cold email campaigns including 1-8 messages in the sequence, to 50 prospects a day, at a moderate pace, the default SMTP service of your email provider should work just fine for you.

Usually, external SMTP providers offer you higher daily limits than the major email service providers. So if you’re planning an occasional more intense frequency of sending for one of your campaigns, you may think about that.

What’s important, however, the dedicated IP of impeccable reputation that I mentioned in my mailman metaphor is something you actually need to pay extra for. So, to be clear, external SMTP providers won’t offer you the dedicated IP with excellent reputation by default in each of their pricing plans.

But above all that…

A great IP won’t do the 100% job for good deliverability!

Remember that the mailman delivering your message is just one factor affecting deliverability.

If you have the best mailman, but you have him deliver sloppy, irrelevant messages – people won’t like to get the messages anyway…

So if even if you use a dedicated IP, but you send low-quality messages to thousands of poorly targeted prospects, you won’t get positive results. In fact, your crappy messages may in the long run spoil the great reputation of your dedicated IP. So this way, you’re just burning your money.

Don’t think of an external SMTP option as an opportunity to send more messages in the “throw spaghetti at the wall and see what sticks” fashion.

Instead, treat it as an opportunity to have more deliverability factors under full control. And take a good care of the quality of your outreach to make sure deliverability is at its highest possible levels.

When you might want to use an external SMTP service?

I mentioned before that the external SMTP may be a good option in some specific situations. Here are some examples:

  1. If you’ve put a lot of work to improve your deliverability rates (aka, you’ve checked the 14 points on the deliverability checklist), and you still have reasons to suspect the deliverability of your messages might me at a low level, you may try an external SMTP to control the reputation of your IP. But leave it for the end of the list while working on your deliverability.
  2. If you’re using Woodpecker’s email automation to send messages other than cold emails – which require higher frequency of sending, or have to be sent in greater batches at a shorter time, like for instance automated retention emails to your SaaS users – you may want to think about an external SMTP service.
  3. If you’re organizing an event and you want to send emails to a greater number of the event attendees at short notice, you may want to use an external SMTP to be able to send more messages faster for this specific occasion. Keep in mind, though, that these prospects should be interested in your message and happy to engage with it, if you want to see satisfactory effects. Again, don’t send leaflets to just anyone there is, because it will ruin your outreach no matter what you use to send it out! Take care of precise targeting. Always.

What are the companies offering an external SMTP service?

Woodpecker has been designed to send messages from your own mailbox, so we do not offer external SMTP services. But if you wish to connect an external SMTP service to Woodpecker, it’s possible.

There are quite a few companies offering external SMTP services, actually. You can check those 2 collections to find some names, descriptions, pricing and more:

Final words

Before you decide to try out an external SMTP service to send your cold email campaigns, make sure you’ve done everything else to improve your deliverability rate. If you go for a dedicated IP without taking care of your email copy, the quality of your prospect base, and some basic settings – it’s all for nothing, because after sending a first larger batch of emails, even from an ideal IP, your deliverability will drop down anyway.

Check out this guide on connecting Woodpecker with an external SMTP >>


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