How to Know If Your Emails Are Actually Getting Through

TL;DR

“Delivered” in your ESP just means the receiving server accepted the email. It does not mean it reached the inbox.
Delivery and deliverability are two different things. Both matter for recruiters.
You can test inbox placement before you send, and diagnose what went wrong after a bounce.
The tools are free or cheap. The process takes about ten minutes. The cost of not doing it is candidates who never hear from you.

Recruitment runs on email. Candidate outreach, job alerts, interview confirmations, client updates, timesheets and more. If your emails are not getting through, your business is running on a leaky pipe and you probably do not know it.

The most common question we hear from agency owners is some version of: “How do I actually know if my emails are reaching people?”

It is a good question, and the honest answer has two parts. There is what your email platform tells you, which is useful but incomplete. And there is what is actually happening at the inbox, which requires a different set of checks entirely.

This post covers both. By the end, you will know how to read what your ESP is telling you, how to run a proper inbox placement test, what bounce codes mean in plain English, and what to do when something looks wrong.

Delivery vs Deliverability: The Distinction That Matters

Before anything else, it is worth being clear on what these two words mean, because they are often used interchangeably when they should not be.

Email delivery is the technical handshake. When your sending server passes a message to the recipient’s mail server, and that server responds with an acceptance, your email is considered delivered. Your ESP will log this as a successful send. The message left your system and was accepted at the other end.

Email deliverability is what happens next. Does it go to the inbox? The junk folder? Does it get silently dropped? Does it sit in a promotions tab where your candidate never looks?

Delivery is binary. The server either accepted it or it did not. Deliverability is a sliding scale, shaped by your domain reputation, your authentication setup, your sending behaviour, your content, and how recipients have engaged with your emails historically.

For a recruitment agency, both matter. A hard bounce is a delivery failure. Emails that consistently land in spam are a deliverability failure. They have different causes and different fixes, but both result in the same outcome: the person you emailed did not read it.

What Your ESP Dashboard Is Actually Telling You

Whether you are sending from your ATS, Mailchimp, HubSpot, or a sequencing tool like SourceWhale, your sending platform will show you a delivery rate for each campaign or send. Here is how to read it accurately.

Delivered: The receiving server accepted the message. Nothing more, nothing less. A 99% delivery rate does not mean 99% of your emails reached an inbox. It means 99% were not bounced at the server level.

Opened: Someone loaded the email. Treated as a useful signal, not a reliable one. Apple’s Mail Privacy Protection has inflated open rates significantly since 2021. An “open” from a candidate who uses Apple Mail might be an automatic pre-load, not a human reading your message.

Clicked: More reliable than opens. If someone clicked a link, they were in the email. This is your most useful engagement metric.

Bounced: The server rejected the email. This is where the useful diagnostic information lives. More on this below.

Unsubscribed / Spam complaint: Someone actively flagged your email as unwanted. For recruitment outreach, a high complaint rate will damage your domain reputation with Gmail, Outlook, and Yahoo faster than almost anything else.

The delivery rate figure your ESP shows you is a starting point, not a verdict. If you want to know where emails are actually landing, you need to run placement tests.

How to Run an Inbox Placement Test

An inbox placement test sends your email to a set of seed addresses across different providers (Gmail, Outlook, Yahoo, Apple Mail) and tells you exactly where it landed on each one: primary inbox, spam, junk, or promotions.

This is the closest thing to an objective answer to “are my emails reaching people?” that you can get before pressing send.

Mail-tester.com (free, quick, great for a one-off check)

Mail-tester gives you a temporary email address. You send your email to that address, come back to the site, and it returns a score out of 10 with a breakdown of what it found: your authentication records, spam score, content signals, and blacklist status.

It is useful as a pre-flight check before a campaign. If your score is below 8, something needs fixing before you send.

One thing to be clear on: Mail-tester checks whether your email looks trustworthy to spam filters. It does not test actual inbox placement across a range of real providers. For that, you need GlockApps.

GlockApps (paid, but worth it for campaigns)

GlockApps sends your email to a network of real seed inboxes and returns a placement breakdown showing which providers put you in the inbox, which put you in spam, and which in a secondary folder. It also shows your domain and IP reputation, and flags authentication issues.

For a recruitment agency running regular candidate outreach campaigns or job alert sends, a GlockApps test before a large send is sensible practice. We cover it in more detail in the Advanced Delivery Testing post.

The manual seed list approach

The low-tech version: set up test addresses at Gmail, Outlook.com, and Yahoo Mail. Before you send a campaign, send to those three addresses and check where it lands. Not as comprehensive as GlockApps, but free and takes two minutes.

Reading Bounce Data: What the Codes Mean

When an email bounces, your ESP records a bounce code. Most platforms summarise this as “hard bounce” or “soft bounce,” which is a useful shorthand but the underlying code tells you far more about what actually happened.

Hard bounces

A hard bounce means the server permanently rejected the email. Common causes:

The email address does not exist
The domain does not exist
The receiving server has permanently blocked your sending domain or IP

Hard bounces should be removed from your list immediately. Continuing to send to addresses that hard bounce damages your sender reputation with every major inbox provider. If your bounce rate on any send exceeds 2%, that is a red flag.

Soft bounces

A soft bounce is a temporary rejection. The address is valid, but the server could not accept the message right now. Common causes:

The recipient’s mailbox is full
The receiving server is temporarily unavailable
Your message was too large

Your ESP will typically retry a soft bounce automatically for 24 to 72 hours. If it continues to fail, most platforms will eventually reclassify it as a hard bounce.

Block bounces

Block bounces are worth knowing about separately, even though many platforms lump them in with soft bounces. A block bounce means the receiving server actively rejected your message based on a reputation signal. Your IP, your domain, or your content triggered a filter.

Block bounces are a sign that something is wrong with your sending reputation or configuration, not with the address itself. If you start seeing a pattern of block bounces across a send, that warrants investigation rather than just retrying.

An important nuance: corporate vs personal mailboxes

Bounce behaviour differs depending on whether you are sending to personal mailbox providers (Gmail, Yahoo, Hotmail, iCloud) or corporate platforms (Microsoft 365, Google Workspace).

Personal mailbox providers are less likely to issue a hard bounce when they filter your email to spam. They may simply accept the message silently and drop it into junk, with no bounce at all. This means your ESP can show a clean delivery rate while your emails are sitting in spam folders.

Corporate mail platforms tend to be more communicative when they block a message, often returning a bounce code with a reason. This is actually more useful for diagnosis, even if it feels worse.

The implication for recruiters: a low bounce rate is not enough evidence that your emails are reaching people. You need placement tests, not just delivery reports.

Common SMTP Bounce Codes Explained

When you look at the raw bounce data in your ESP, you will often see a three-digit code with a message. Here are the ones you are most likely to encounter:

550 — User unknown, or mailbox not found. The most common hard bounce. The address does not exist.

551 — User not local. The receiving server is telling you to try a different address. Rare.

552 — Message too large, or mailbox over quota. Content or size issue at the recipient’s end.

553 — Mailbox name not allowed. Often a formatting issue with the address.

554 — Transaction failed. This is the generic rejection code. The accompanying message usually gives more context — look for phrases like “spam detected,” “policy violation,” or a specific blacklist name. This is where block bounces typically show up.

421 — Service temporarily unavailable. Soft bounce. Try again.

450 / 451 — Requested action not taken, or server error. Soft bounce. Usually transient.

If you see a 554 with a reference to a blacklist in the bounce message, that is the most actionable signal you can get. It tells you specifically which blacklist your domain or IP has been flagged on, and most blacklists have a delisting process you can follow.

Google Postmaster Tools: Your Ongoing Reputation Monitor

For recruiters sending to Gmail addresses (which is most candidate outreach as they tend to use personal Gmail accounts), Google Postmaster Tools is essential.

It is free. You verify your domain, and Google gives you visibility into:

Your domain reputation with Gmail (high, medium, low, or bad)
Your spam rate as reported by Gmail users
Authentication pass rates for SPF, DKIM, and DMARC
Delivery errors

The domain reputation signal is the most important for recruiters. If it drops to “low” or “bad,” your emails to Gmail addresses will land in spam regardless of how good your content is. The fix is not to write better subject lines. The fix is to address whatever drove the reputation drop (usually high complaint rates, high bounce rates, or authentication failures).

We have a full post on how to set up and read Postmaster Tools if you want to go deeper.

What to Check When Something Looks Wrong

If your open rates have dropped, you are getting unusual bounce volumes, or a candidate or client has told you your emails are not arriving, here is the sequence to work through.

First: check your authentication. Run your domain through MXToolbox or Mail-tester.com and confirm that SPF, DKIM, and DMARC are all correctly configured and passing. Authentication failures are the single most common root cause of deliverability problems, and they are invisible unless you look for them. Nearly half of the 490 UK recruitment agency domains we assessed had no DKIM record in place.

Second: check the blacklists. MXToolbox has a free blacklist checker. If your domain or sending IP appears on a major blacklist, that will explain block bounces and spam placement. We have a detailed post on MXToolbox and how to interpret what it tells you.

Third: run a placement test. Send a live version of your email through GlockApps or to a set of seed addresses across Gmail, Outlook, and Yahoo. If it is landing in spam, you need to know which providers are treating it that way and whether the cause is authentication, reputation, or content.

Fourth: check Google Postmaster. If Gmail is the problem, Postmaster will usually tell you why. Look for spikes in your spam rate and any drops in domain reputation.

Fifth: look at your recent sending behaviour. Did you send to a large or old list recently? Did you import contacts from a source that had not been cleaned? A single send to a stale list can cause a bounce or complaint spike that takes weeks to recover from. List hygiene matters more than most agencies realise.

If you have worked through those five steps and still cannot identify the cause, the problem is likely in your sending infrastructure or domain configuration, something that requires digging into message headers and DMARC reports rather than surface-level tooling.

What This Means for Recruiters

Recruitment agencies send a particular type of email that is inherently hard to land in inboxes. You are often sending to people who did not request your message. You are sending at volume. You are sending similar content to large lists. And you are doing it from the same domain you use for everything else (client proposals, contracts, job offers).

That combination means your delivery health needs active monitoring, not just occasional attention. A problem that develops quietly over six months (rising complaint rates, declining engagement, gradual reputation degradation) can surface suddenly as a deliverability crisis that takes your outreach offline at the worst possible moment.

The tools covered in this post are free or low-cost and take minutes to run. The question is whether you make them part of a regular process, or wait until a candidate tells you your emails are going to spam.

Frequently Asked Questions

What is the difference between email delivery and email deliverability? Email delivery is whether the receiving server accepted your email. Deliverability is whether it reached the inbox. A high delivery rate does not mean your emails are not going to spam. It just means they were not bounced at the server level. You need inbox placement tests to understand deliverability.

Why does my ESP show a 99% delivery rate but candidates say they are not receiving my emails? Several things can cause this. Personal mailbox providers like Gmail and Yahoo often accept emails and filter them to spam without issuing a bounce, so your delivery rate stays high. Authentication failures, domain reputation issues, or content flagged by spam filters can all cause inbox placement problems without showing up as bounces.

What should I do if I get a hard bounce? Remove the address from your list and do not send to it again. Hard bounces mean the address is invalid or your domain is blocked. If you get a significant number of hard bounces in a single send (over 2%), investigate the source of those addresses and check whether your domain or IP has been blacklisted.

How often should a recruitment agency run inbox placement tests? Before any large send to a cold or semi-cold list, and any time you notice a drop in open rates or engagement. For agencies doing regular outreach campaigns, a monthly check is sensible. For one-off sends, run a test before you go live.

Can I tell if a specific email went to spam? Not directly, unless you have access to the recipient’s inbox. What you can do is run placement tests against representative seed inboxes, monitor Google Postmaster for Gmail-level signals, and look at your engagement data for patterns that suggest inbox placement problems. We cover this in more detail in our post on whether you can tell if an email landed in spam.

What is an rDNS error in a delivery test, and should I be worried? Reverse DNS (rDNS) errors appear in tools like MXToolbox and Mail-tester if your sending IP does not have a matching PTR record. If you are on Microsoft 365 or Google Workspace, this is expected, You share Microsoft’s or Google’s IPs and cannot set your own rDNS. It is not a problem in practice for most recruiters. We have a full post explaining rDNS issues in delivery tests if you want the detail.

Ready to Fix What You Find?

Testing your email delivery is the diagnostic. If the results show authentication failures, blacklist entries, or consistent spam placement, you need someone who understands both the technical fix and the recruitment context to put it right.

That is what Quinset does. Book a call with Ben and we will tell you exactly what is wrong and what to do about it.