Using an external SMTP server to send unlimited emails with Gmail and GMass

This article is a guide for GMass users that want to start using SMTP-based sending for their email campaigns in Gmail using GMass. Last week I announced this feature was coming, and starting today, we’re asking users to begin testing.

The advantage of this setup are:

  • The ability to send virtually unlimited emails and not be constrained by Gmail’s sending limits.
  • No risk of an account being suspended by Google.

The disadvantages of this set are potentially:

  • A slight decrease in deliverability, although from our testing, we’ve found the deliverability using Sendgrid as the SMTP server to be just as high as sending natively from Google.

Choosing an SMTP server

You have two choices to connect your GMass account to an SMTP server:

  1. If your email sending meets certain criteria, you can use my SMTP server, which is a high volume server with Sendgrid. Your email sends must be either a) non-commercial in nature (like school groups, membership clubs, social causes, churches) or b) completely organically developed. So, your emails can be of a commercial nature if your list is completely organic. If that’s the case, you’re welcome to use the SMTP service I have with my Sendgrid account. Contact us at to make this request, and state the nature of your email sending.
  2. If your email does not match this criteria, or you just want to use your own SMTP service, then feel free to set up an account on your own with SendgridJangoSMTPMailjet, or any other SMTP service provider. Your company may even have its own SMTP server that you can use. In a future post, I’ll be analyzing the popular SMTP providers, also known as transactional email services, and explaining which ones I think are the best and worst. Once you set up an account with an SMTP service provider, you’ll have to configure the account in certain ways. Read on…

Configuring your SMTP service account

  1. GMass will connect without TLS/SSL to the SMTP server on the port of your choice. Most SMTP services allow you to connect on ports 25 and 2525 at a minimum.
  2. Ensure that open and click tracking are turned OFF with the SMTP server service. In fact, the SMTP server shouldn’t alter the message at all. It should just pass it through. This is because GMass will add the tracking for you if you set your tracking this way, and we don’t want the emails to be “double” tracked. Screenshot from Sendgrid:
    Sendgrid Tracking
  3. Ensure there are no quota restrictions on your SMTP account, or if there are, that they are sufficient to handle your GMass campaigns.
  4. Check to see what Envelope From, also known as MAIL-FROM or RETURN-PATH address your SMTP service will use when relaying your email. Most transactional email services like Sendgrid use a domain by default, which makes it so you don’t necessarily have to alter your SPF records. Some SMTP services require domain verification, because the domain in your From Address will be the domain in the MAIL-FROM. Just be aware of this. You may need to alter your SPF, DKIM, and DMARC records.
  5. Ensure that Bounce Notifications are on. Set them to go to the From Address. This will allow GMass to process your bounces, just like normal. Not all SMTP services have this capability. Sendgrid and JangoSMTP do. Mailgun and Mailjet do not. Screenshot from Sendgrid:
    Sendgrid Bounce Settings

How to set your GMass account to send emails through an external SMTP server

GMass SMTP Configuration
Configure your GMass account to send via an external SMTP server instead of your Google account. The Sendgrid credentials show above are not real.
  1. First, reload Gmail in your Chrome browser to make sure you have the latest version of GMass.
  2. Click Compose to launch a new window.
  3. Set the To field to
  4. Set the Subject to the word set. Wait a second for the form to appear in the Message area.
  5. Enter the SMTP server, port, username, and password after the colons.
  6. Hit the GMass button. Do not hit the Send button.

GMass will attempt to relay a test message through the server to yourself. If successful, the SMTP server will be set for your account.

To clear out the SMTP settings, set the Subject to “clear”. To view the SMTP setting currently on your account, set the Subject to “status”.


Q: What’s going on here? How do I use an external SMTP server and send unlimited emails from my Gmail account?

A: If you’re sending non-commercial emails, you can use my SMTP account with Sendgrid. Or, you can create your own account with a service like Sendgrid, Mailgun, Mailjet, or JangoSMTP.

Q: Do you charge more for sending this way?

A: Currently, we are not charging any extra for relaying email through an external SMTP server, whether it’s our SMTP account you’re using or one you set up externally. Your only additional costs will be the cost with the SMTP service provider, which may be an additional $10+/month, based on what kind of account you get. So theoretically you could pay $12.95/month to GMass for a G Suite Standard account, and pay Sendgrid an additional $9.95/month and send 40,000 emails/month or $19.95/month and send 100,000 emails/month. For certain campaigns, you could disable SMTP sending and send natively through your G Suite account, allowing for another 1,500-2,000 emails/day.

Q: Is this SMTP option available for free GMass accounts, or do I need to have a paid GMass account?

A: It will work with a free GMass account as well, but using this option with a free GMass account defeats the purpose. GMass already limits free accounts to sending 50 emails per 24 hours, which is well under Gmail’s own limits, so connecting to an SMTP server to send high volume campaigns wouldn’t solve anything, since GMass will already limit you to 50 emails per 24 hours.

Q: Why should I use two services, yours and an external SMTP provider, when I could use one service like Sendgrid, which also supports sending newsletters?

A: You are free to use any service you like, but we think that GMass with an external SMTP service makes for a powerful combination for email marketing and email automation. The ease and familiarity of the Gmail interface makes sending an email campaign a time efficient process. Additionally, by combining GMass and an external SMTP service, you can send virtually unlimited emails with the auto follow-up feature, a feat that would be impossible without GMass, since GMass integrates with your Gmail Inbox. Using just Sendgrid in a standalone fashion won’t accomplish that.

Q: I’ve read that Gmail doesn’t allow its users to send “from” their Gmail accounts using outside servers. So how are you getting away with this?

A: It was thought that in early 2017, Gmail was going to update their DMARC policy to reject emails that are “from” a address and sent by a non-Gmail server. Here’s some more detail on that prediction. That change hasn’t happened yet though. Here is Gmail’s DMARC record as of 9/28/17 11:24 AM CST:

Gmail’s DMARC policy hasn’t changed yet to reject emails sent “from” from a non-Gmail server. Once they change it, p=none will become p=reject.

If you are sending campaigns from your address rather than your organization’s G Suite address, then this policy is relevant to you, and we’ll be monitoring it for changes. In our testing so far though, we’ve only found one email provider, AOL, that routes emails that match this criteria to the Spam folder. Even Gmail doesn’t reject email that is sent from an address by a non-Gmail server. For example, in my testing, I sent email “from” through to my account, and the email arrived just fine to my account. If you are sending from your G Suite address, then you don’t need to worry about this policy at all, because you get to set your own policy!

Q: In my Gmail Settings under “Send mail as”, I can add another From Address to use, and then Gmail asks me to specify an SMTP server. How is that different from specifying an SMTP server this way?

A: When you set up a new From Address in your Gmail account, if the From Address is a non-Gmail address, then yes, you are asked to set an SMTP server. However, even in that case, the Gmail sending limits still apply, even when Gmail is sending the emails through your own SMTP server. That’s because Gmail is still “handling” the email sending, but just routing it through the server you specify. With this way, Gmail isn’t “handling” any of the email sending, so the limits won’t apply.

Q: I want to send a 100,000 email campaign using GMass and Sendgrid. How long will it take my campaign to send?

A: Admittedly, because of how we are sending these emails, we have not optimized this process for speed. If you need to get 100,000 emails out in an hour, then this isn’t the right solution. The rate of sending will be around 3,500 emails/hour. Why so slow? Because the processing power of both sending the email through an external SMTP service AND making sure your Gmail account knows about it is a “costly” procedure, from a computing perspective. So, if you need to send 25,000 emails throughout the course of the day, then this could work well for you. But if you need to send, 25,000 emails in the next ten minutes, this is not the solution for you.

Q: Do I need to worry about SPF, DKIM, and DMARC?

A: It depends on which SMTP service you choose and whether you’re sending from an address or a G Suite address. If sending from an address, you don’t need to worry about any of this. If sending from a G Suite address, then it depends on the SMTP service you choose. The default setup with Sendgrid is such that you do NOT have to worry about SPF, DKIM, and DMARC. This is because in the default setup the MAIL-FROM used in email sending is a address, so the SPF and DKIM signing is taken care of by Sendgrid’s DNS records and infrastructure. If you opt for Sendgrid’s “whitelabel” option though, then the MAIL-FROM can be based on your own domain, and then you would need to ensure that SPF is set up to allow sending from your domain through Sendgrid, and you can then have emails DKIM-signed by your own domain as well. For other providers, like Mailgun, for example, you have to “whitelabel” your domain from the outset, and handle SPF/DKIM from the outset. Therefore we can conclude that getting set up on Sendgrid is easier because they don’t require this setup.

Q: Do you recommend certain SMTP services over others?

A: There are many SMTP services to choose from, including Sendgrid, JangoSMTP, Mailgun, Mailjet, SparkPost, Amazon SES, and others. Each has its strengths and weaknesses, and I’ll be detailing all of these in a future blog post. I’ve been testing extensively with Sendgrid, and so far, I’ve found it to be a good fit for this solution, because it doesn’t require any domain verification to get started and it sends bounces back to you. That’s not to say that another service wouldn’t fit you just as well. Personally, I’m most familiar with Sendgrid and JangoSMTP. Full disclosure: I created JangoSMTP back in the early 2000s, and it was acquired in 2013, but I’m still close to the JangoSMTP team.

10 Replies to “Using an external SMTP server to send unlimited emails with Gmail and GMass”

  1. Domagoj Marenic

    Does external smtp work on hosting smtp, and is available to google suit services? I see the use of you did not specify, and it allows all google users 10,000 email messages per day which is quite enough for most, and stays in and continues to send mail via gmail service.

  2. Whitney Ludwig

    getting an error when i try to enter the smtp server, port, username, and password.

    I’m using gmail and sendgrid.
    error occurs when I press the gmass button after filling out the form to send.

    error is:
    Your GMass request failed. Error details: Index was outside the bounds of the array.

  3. Josh

    Would it be possible to see any stats on deliverability with the 3rd party? We tried with sendgrind before and this reduced deliverability 90% over using gmail servers.

    Great tool 🙂 Much thanks!!

  4. adam sert

    when i do all configuraion and and click at Gmass , it give me that message

    Your GMass request failed. Error details: Index was outside the bounds of the array.

    • Maya Quijada

      This is a temporary error and should go away if you refresh Gmail in Chrome and try again (don’t worry, you won’t lose your work). However, it depends what you’re trying to do – if that doesn’t work, will you send us an email at Our support team will give you a hand.

  5. Lee Robertson

    I can’t say much right now I have to work with GMass a little longer, I still trying to understand how it works. The little I know about GMass I love it!

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