Email Verification Service Provider Comparison

Email Verification Service Provider Comparison

Email deliverability has been a hot topic for marketers for quite some time. With mailbox providers getting more aggressive about their spam blocking and filters, inbox placement has become a priority issue for many marketers to address. To protect their email deliverability, marketers need to implement email verification as part of the pre-campaign routine. In this article, we are comparing a few email verification service providers to help you find the one that will keep your email list clean.

Why Verify Your Email List?

Email deliverability is a complex topic, but it comes down to 3 things:

  1. Sender reputation, this includes sender email/domain as well as IP address it sends from.
  2. List and content quality.

So deliverability is strongly correlated to your sender reputation and hard bounce rate is one of the factors affecting it. With high hard bounce rates sender reputation takes a hit. If you don’t implement any actions to reduce your bounce rate it can negatively impact your inbox placement. Your domain might get marked as SPAM by Internet Service Providers, which can result in your emails being delivered to the SPAM folder, and even lead to getting your domain appear on blacklists.   

Risk of Account Suspension with Your ESP

An average email list decays at a rate of 2% per month for B2C lists and 3% for B2B lists. So if an email list hasn’t been engaged in more than 3-4 months it can have more than a 10% bounce rate on the first bulk campaign. A bounce rate over 10% can result in getting an account suspended on many email platforms, in addition to causing long-term damage to your sender reputation. 

About Catch_all and Accept_all emails

Email verification will also prevent you from sending your campaign to disposable (aka temporary) emails as well as emails that domains set up as catch_all. Disposable emails are often used by spammers and fraudsters. Once created they usually are valid for around 48hrs, and later become invalid emails that will generate hard bounce. Catch_all also known as Accept_all emails, is an address that is specified to receive all messages that are addressed to an incorrect email address for a domain. The risk with such emails is that it might seem to be valid, however, it could still generate a hard bounce. By using email verification you will be able to establish which of the addresses are set up as catch_all, but you won’t learn if it is deliverable or not. The decision to message such addresses should be based on the overall quality of your list.

Email Bounces and Cost

There is of course a budget factor – email verification can save you money. Sending your campaign to undeliverable or risky addresses via your ESP’s or marketing platform can generate extra costs, with no chance of generating any return on investment (ROI).

Verification Process and Results

In a typical verification process you upload a CSV file and once validation is complete you see stats on the results and options to download your verified list. Most verification services produce at least these 4 statuses:

  1. Deliverable – these emails are safe to send to
  2. Undeliverable – these addresses no longer exist and should not be sent to
  3. Risky – these emails are likely to result in a high bounce rate (often catch-all addresses)
  4. Unknown – these emails couldn’t be verified so may result in high bounce rate.

If your email verification provider allows it, you should download Deliverable, Risky, and Unknown as separate lists and upload them as separate lists into your email marketing platform. If you are starting fresh with a new service provider you should ONLY send your 1st campaign to Deliverable addresses only, to ensure the lowest possible bounce rate. This is because many providers move you onto a shared IP pool tier that correlates to your 1st campaign or campaigns sent in the first 1-2 days.

On average, email lists identified as Risky or Unknown by email verification providers result in 30% bounce rate, so they should be slowly added into large bulk campaigns overtime, to finalize verification through sending.

While bounce rate below 10% will not result in you getting banned from an email marketing platform your goal should be to keep bounce rate below 3% for best email deliverability.

Choosing an Email Verification Service

There are a lot of email verification services available, and it might be overwhelming when searching for the right one for the first time. There are several methods used by providers to verify emails so there is a small variation in results and accuracy. We find that the difference in accuracy is fairly small – around 2% – while the cost can vary x2-5.

For this comparison article, we are focusing more on affordable providers we have evaluated as potential partners. BigMailer is a very affordable email marketing platform, so it was important for us to continue to offer our customers great value when integrating a 3rd party email validation service. 

Other factors that we considered besides cost are: security and GDRP compliance, availability of robust APIs to process large data sets, possibility to run a test prior to purchase, and finally the team behind the service and support. 

Below are the services we had reviewed and ranking factors we have checked for this article:

email verification provider comparison 2022

Last Updated: Mar 14 2022

As we were evaluating prospecting partners 2 services stood out (and we got you extra discount with both):

Bouncer verification resultsBouncer

Bouncer has easy-to-use UI and very flexible data download options, making it our favorite. You even get options on what columns to keep or add to your final verification results, which can simplify your workflows post verification. These options are especially helpful for large list owners, since large data files can become a blocker for importing a list into an email marketing platform.

Bouncer offers you an option to run a free bounce rate estimate, which helps you decide if you need to verify your list. The estimate only takes a few min to generate and can be incredibly useful.

Bouncer team and servers are located in Europe so this can appeal to organizations in the EU region. Bouncer file upload limit is 500,000 emails or 30MB in file size. Get a 10% discount with this link.


Emailable offers good verification speed on large lists and 1500 free validation credits to BigMailer customers via this link only. Emailable file upload limit is 1 million emails and 100MB in file size, which can be useful for large list owners. 

We also like Emailable Deliverability Monitor service – $149/month for up to 50 domains/IPs with 12-hr checks.

Both providers have de-duplication but they act on it differently:

  1. Emailable automatically de-dupes your list but doesn’t display the info on results so it can be confusing why your output list is smaller than the list you uploaded.
  2. Bouncer automatically de-dupes and displays the stats.

Neither service is offering ability to identify spam traps, a feature very few providers offer at a higher than usual verification cost.

About Spam Traps

Spam traps are used to identify and monitor spam email by Internet Service Providers (ISPs), anti-spam organizations, and blocklist operators. They are email addresses (also called honeypots) used to identify senders who aren’t following email best practices. If you either purchase your email lists or scrape email addresses from the web there is a good chance you have a lot of spam traps on your list. 

Learn more about avoiding, identifying and removing spam traps in our article on spam traps. If you are a BigMailer customer you can reach out to us to help you determine if this is an issue for you and what provider would be best for removing spam traps from your list. Not a BigMailer customer? Get started with a free account.

Happy email marketing! 

Advanced Deliverability and Inboxing Optimizations

Advanced Deliverability and Inboxing Optimizations

Email deliverability is the ability to deliver emails to subscribers’ inboxes, while email delivery refers to ability to deliver email to mailbox provider server. So when an email service providers (ESP) boast high deliverability they don’t usually mean high inbox rate. Emails delivered are emails not rejecting by the mailbox provider, so emails in a spam folder are considered delivered.

This article focuses on advanced deliverability topics, so make sure to review our email deliverability guide to best practices first.

What happens when an email isn’t accepted? A few things, like:

  1. Hard bounce means an email address is no longer valid. No future re-delivery attempts are made.
  2. Soft bounce can happen for several reasons:
    • Mailbox provider service is temporarily down.
    • Recipient mailbox is full.
    • Email is rejected. No further attempts to deliver are made automatically.
  3. Email delivery is delayed. Several attempts are made to re-deliver for up to two days, until the email is either rejected or delivered. The first attempt to re-deliver is made in about 20 min, then a few hours. This is why your campaign may appear either healthy or with low engagement, but the soft-bounce rate can jump the day or even two after a campaign is sent.

Common Rejection (Non-Delivery) Reasons:

  1. Higher than typical volume compared to recent history for a sending domain. Large list jumps of 50% or more from one day to the next indicate inorganic list growth due to list renting/purchasing. What’s a safe sending rate increase for a sender domain warmup? It depends on the starting point and how far along in the warmup your domain is.
    • For list sizes under 50K you could increase by 20-30%/day
    • For list sizes over 300K you should stay under 20% per day
    • A brand new domain should start at around 100-300 emails per day and can go up by 50% while under 10k/day, as long as the list is diverse – meaning it’s not 50%+ gmail/yahoo/aol only.
  2. Sender domain reputation – this is a combination of:
    • Hard bounce rate – historical and immediate.
    • Historical complain rate.
    • Sending to spam traps.
    • Reputation of the IP address sending emails. Unless you are paying for a private/dedicated IP address your emails go out from a shared IP pool, meaning a set of IPs used by many senders.
  3. Historical and recent low engagement. This can be split into 2 separate issues:
    • You may see 20-35% on your daily or weekly campaigns, but if it’s the same subscribers opening your emails and 75% of your list is completely inactive that’s a problem.  Mailbox providers don’t like seeing sending activity with no engagement, they see it as abusive and low quality practice.
    • You may see a 20-25% open rate for your campaigns, but upon closer inspection an engagement by mailbox providers report may show that your open rate is high for some providers and very low for others. If you start seeing an open rate drop below 3% for a specific mailbox provider, e.g. yahoo/aol, you need to make adjustments to your sending strategy to avoid rejections.

Tactics to Improve Deliverability and Inboxing

Remove Spam Traps

A common tactic to improve your sender reputation is to remove spam traps from your email lists. Spam traps are used to identify and monitor spam email by Internet Service Providers (ISPs), anti-spam organizations, and blocklist operators. They are email addresses (also called honeypots) used to identify senders who aren’t following email best practices. If you either purchase your email lists or scrape email addresses from the web there is a good chance you have a lot of spam traps on your list. Learn more about avoiding, identifying and removing spam traps in our article on spam traps. If you are a BigMailer customer you can reach out to us to help you determine if this is an issue for you and the most cost effective way to remove them.

Improve Engagement

The best way to address both low engagement and high complaint rate is to reduce sending frequency, especially to inactive subscribers on your list. When someone checks their email infrequently and they see 2+ daily emails from the same sender they are more likely to complain (report as Spam, or move to Spam folder) and they can flag every email from a sender, not just one.

Good send time is 6am-3pm local time Monday-Friday, while 7am-10am Tuesday-Thursday is typically best. That’s because most emails are checked during typical work hours. Avoid sending after 5pm on a work day – it’s a very low engagement time of day. If you don’t have location for your subscribers you should start earlier and if you do then it’s best to optimize for local time.

Mailbox providers like Gmail and Hotmail are very sensitive to historical engagement. What this means is this – if a recipient doesn’t open 5+ emails from a sender in a short period of time (< 2 weeks), the future emails are highly likely to go to Spam. You can test this with your own seed email accounts. The only way to override this behavior is by dragging an email out of Spam folder or labeling it as “Not Spam”. So when you reduce your email frequency you improve your chances for having the recipient open your email before they start going into Spam folder.

Sounds like a lot of work? It doesn’t need to be – you can automate many things in BigMailer. Consider defining reusable segments to use in your campaigns. To create a segment go to Lists tab and click on All Contacts list, click on Search and specify your segmentation rules, then use “Save as a Segment” button. Once a segment is created it can be edited anytime.

Here are some segmentation rule examples that may help:

  1. Recently Active – Opened/Clicked Any Campaign in the last X days or recently added Engaged Segment ExampleThen you simply match that segment in your campaign: Campaign segment match
  2. Inactive audience can be used to send less frequent campaigns with the goal of re-activating. Be careful though – re-activation campaigns may cause a higher than usual complaint rate. You could simply use the same segment you defined for active subscribers but with the rule “does not match”. Campaign segment no match

Consider your sending frequency when deciding how to define your active subscribers. If you are sending daily, perhaps you only send to those who opened in the last 3-4 days. If you send weekly, a 14-21 day timeframe would be reasonable.

Special Case: Automated RSS Campaigns

If you use a daily automated RSS campaign you could consider reducing frequency from daily to once a week for anyone who doesn’t open any campaigns for 3-4 days, using the same segmentation rules discussed above. You could create a separate RSS campaign and use a reverse rule on a segment so your audience shifts from daily to 1/week automatically and as soon as they open they will shift  back to daily campaign again. You could even take this further and setup a 3rd campaign where audience shifts with no opens in 30 days. This helps you avoid sending to inactives and avoid spam folder overall.

RSS campaigns

Example: RSS campaigns to active and inactive contacts

If you are a BigMailer customer you can reach out to us via chat to get our assistance with your deliverability. Not a BigMailer customer? Get started with a free account.

White Label Setup FAQ

White labeling BigMailer platform offers several benefits, but may not be necessary to meet your needs. This article helps you understand the pros and cons of using a white label and any limitations to supporting your use case and requirements.

BigMailer unsubscribe page customizationsSome email platforms refer to white label as an ability to brand your unsubscribe page and setup a a custom domain for links in the email and to host your unsubscribe page. This option is available to BigMailer customer on all plans at no extra cost.

In BigMailer you can customize the Unsubscribe page for each brand by adding a logo, custom message, and message types to manage it as an email preference center.

What BigMailer calls white labeling, only offered on Agency and Enterprise plans, is ability to host the platform on your own domain with your logo and all references to BigMailer removed.

White Label Setup

Here is a list of features you can expect with white label:

  1. All users (team members and clients) access the platform via login on your own domain.
  2. All users see your logo in the header, login page, and activity notification emails (account activation, password resets, imports, etc).
  3. The platform will NOT be branded with your colors or styles, but you can still brand your unsubscribe pages (see above).
  4. Error messages and help section will not have any references to BigMailer.
  5. No live chat support from BigMailer team.
  6. Optional: you can provide a link to your own help section if you prefer to manage your own.

What BigMailer white label does NOT support:

  1. Billing your clients for use of the platform. Our white label is not intended for resellers.
  2. Loading the platform or any screens in an iFrame inside another website or application.

Possible Integrations

A lot of businesses are interested in integrating email marketing features into their existing suite of tools. The challenge with a deep integration like that is that you need to re-create a lot of the UI and functionality of an email platform (e.g. email template management, configuration checks, and error handling) and it would likely take many months to deliver. A white label platform allows you to just send the users to the platform that has your branding and uses your business domain in the URL.

Here is a list of APIs you can use with your white label:

  1. Contact management (add, update, delete lists and contacts)
  2. Transactional email campaigns. You can pass entire message body with an API call.
  3. Create new brands, send user invites.
  4. Coming soon: send one-time bulk campaigns.

White Label Assets You Need to Provide

In order to set up your account as white label we request the following assets from you:

  1. White label domain to be used in all URLs
  2. Business name (text label)
  3. A full path to the logo image you want to use – 3 versions:
    a) A logo to appear in the site header, ideally simple and icon like
    b) A logo to appear on the login page, and in transactional emails (login activation, password reset, etc.).
    c) Optional: A path to your favicon
  4. Administrator/support email address that will be referenced in cases of errors (permissions, billing limits, etc.)
  5. Optional: A link to your own help document as an alternative to the help section we manage.

Want to Discuss Your White Label Requirements or Ask Questions? 

Want to explore BigMailer features and UI on your own? Get started with a free account, no credit card required.


How to manage Brands on BigMailer

BigMailer is a platform designed and built for managing multiple brands, which benefits digital marketing agencies, email marketing consultants, franchises, multi-location businesses, and large companies that own multiple brands.

Some email marketing service providers offer “sub-accounts” feature where standalone accounts are linked together and can be accessed with a single login. In this type of setup you login once and can switch between accounts, typically via dropdown in the header.

What is a Brand?

You can think of a brand as a business entity with its own unsubscribe page. So in cases of franchises or multiple locations, each owner or location would become its own brand. The lists can not be shared across brands and billing is based on unique contacts under each brand. A user can be assigned access to multiple brands.

BigMailer allows you to add unlimited brands and users at no extra cost. You have a brand dashboard as a starting point with engagement summary.

BigMailer dashboard - brand list

You invite new users to your account and assign brand access and a role – administrator, brand manager, or campaign manager.

User Management

Brand Names

The brand name is typically the name of the business or the domain name of a website. In cases of multiple locations but same business name it’s best to follow the same naming convention to avoid confusion – location name, or “[main brand] – [location]”.

The brand name is displayed in plain text on the Unsubscribe page unless a logo is uploaded, in which case only the logo is shown and no text. If you don’t upload the logo it’s best to have the brand name label in BigMailer to include actual brand name and not just a location. Below is an example of BigMailer unsubscribe page with logo and custom message types.

BigMailer unsubscribe page

Custom Message Types

Custom message types help manage subscription preferences for your subscribers and can retain more subscribers on your list compared to a single global unsubscribe from a brand.

You can create custom message types under each brand by clicking on the brand name in the header and selecting “Message Types” from the menu. You will not be able to edit message types once you create them, so put some thought into the names before you add them.

Ideally, message types would indicate mailing frequency, if you have a set schedule, for example:

  • Weekly Newsletter
  • Monthly Product Updates
  • Daily Digest
  • Company Announcements (Quarterly)
  • Occasional Offers From Our Partners

You can specify a message type when you create a new campaign and BigMailer keeps track of the subscription preferences.

Gmail Outage Causes Erroneous Hard Bounces

Gmail Outage Causes Erroneous Hard Bounces

You may have heard by now that Google services have experienced major outages on Dec 14 and 15.

Not only Gmail users had difficulties logging into their accounts, but emails sent to Gmail accounts have been rejected by google with:

“code”: “550”,

“extCode”: “5.1.1”,

“message”: “The email account that you tried to reach does not exist. Please try double-checking the recipient’s email address for typos or unnecessary spaces. Learn more at


This means that if you had been sending emails to Gmail addresses during the outage you likely had a high bounce rate for your Gmail addresses and possibly your campaigns and accounts overall. Since BigMailer pauses campaigns with high bounce rate you may have received notifications about your campaigns being paused due to high bounce rate.

You should review engagement by domain report on any campaigns you sent on Monday-Tuesday.

You might see a high hard bounce rate for domain:

high hard bounce rate for gmail emails

If your Amazon SES account got suspended you should reply to the email you received from Amazon and explain that most of the bounces were erroneous from Gmail due to outage (if this is in fact the case). A screenshot of the report, like the example above, and a link to this post may help with a faster resolution and account re-instatement.

While the original issue is outside of our control and influence we are monitoring situation and exploring ways we can rectify it by possibly reseting the bounce status on the affected addresses.

We will post an update once we take any action on this situation. If you need a faster advisory on rectifying this yourself please reach out to us via live chat once you log into your BigMailer account.

UPDATE Dec 17: BigMailer had addressed this issue by reseting the hard bounce status for affected contacts.

UPDATE Jan 6: Most marketers are not even aware of the issue as per the poll we ran on Twitter.