This is week four of Your Summer Email Tune Up. So far we’ve covered domain authentication, domain warming, and why open rates run low. This week zooms out a bit further: deliverability as a whole, meaning your ongoing sender reputation, not just your technical setup.
Here’s the distinction worth understanding.
Authentication and warming are things you set up once and maintain. Deliverability is something you build or damage with every single email you send, based on how your subscribers and inbox providers respond to it over time.
What deliverability actually measures
Every time you send, inbox providers like Gmail, Outlook, and Yahoo are quietly scoring you. They’re watching how many people open, click, reply, delete without reading, or mark you as spam. That score is your sender reputation, and it determines whether your next email lands in the inbox, the promotions tab, or spam, regardless of how well your domain is authenticated.
This means that deliverability problems are rarely due to a single mistake. They build up gradually, from a pattern of signals, which is also why they take time to fix once they’ve gone wrong.
The reputation signals that matter most
Spam complaints
Every time someone marks your email as spam instead of unsubscribing, it damages your reputation with that provider, and it’s a stronger negative signal than almost anything else you can trigger.
Flodesk recently rolled out a direct way to monitor this. You can now connect Google Postmaster Tools to your account under My Account, then Domain setup, which gives you a compliance dashboard showing whether your domain meets Gmail’s sender requirements, including your spam rate.
Once connected, your spam rate also appears in a dedicated Spam rate table on your Emails Analytics dashboard, broken down across Gmail, Yahoo, and Outlook or Hotmail, viewable across several time ranges from the last seven days up to twelve months.
Gmail publishes two clear thresholds here. They recommend staying below 0.10 percent. At 0.30 percent or higher, Gmail will actively block or filter your emails, and this can affect your entire sending domain, not just the campaign that triggered it. This matters because Gmail doesn’t share this data with Flodesk (or other ESPs) directly for custom domain addresses, so before this connection existed, this number was largely invisible to you unless you set up Postmaster Tools separately. Now it lives right inside your Flodesk dashboard.
Note that Google Postmaster Tools only reports data on days you send roughly 50 or more emails to Gmail addresses, so if your list or sending volume is smaller, you may not see Gmail specific numbers on lighter sending days. That’s expected, not a sign something is broken.
Bounce rate
A bounce means the email couldn’t be delivered at all, and there are two kinds. A hard bounce means the address is invalid or doesn’t exist, and Flodesk stops sending to it permanently. A soft bounce means a temporary issue, like a full inbox or a server that’s briefly down, and Flodesk keeps retrying before archiving the subscriber if the pattern continues. Flodesk already helps here automatically: it checks addresses before sending to catch likely hard bounces in advance, and it archives subscribers who soft bounce repeatedly, seven soft bounces with no engagement at all, or up to fifteen if the subscriber has shown recent activity. You can read the full breakdown of how Flodesk handles this here: What Does It Mean When a Subscriber’s Email Bounced.
Even with that built-in protection, a high bounce rate on your side, especially right after importing a list, is still a strong signal to inbox providers that you’re not managing your list carefully.
Low engagement over time
Sending to people who never open or click tells providers your content isn’t wanted, and that assessment doesn’t stay contained to those subscribers. It drags down your reputation for your entire list, including the people who do want to hear from you. This is the core reason list cleanup matters so much, and we’ll go deeper on exactly how to do that next week.
No easy way to unsubscribe
If someone can’t find your unsubscribe link quickly, many will mark you as spam instead, since it feels like the only way to make it stop. That single click costs you far more than a clean unsubscribe would have. Flodesk automatically includes a one-click unsubscribe link in every email, so the mechanism is already handled for you. What’s still on you is making sure that link is actually easy to see.
Check the font size and font color of your unsubscribe footer specifically. Small gray text on a white background is easy to miss, especially on mobile, and a footer someone can’t find works about as poorly as no footer at all.
How your content itself affects deliverability
Beyond subscriber behavior, spam filters also scan the email itself. A few things worth checking:
Text to image ratio: An email that’s mostly one large image with little to no real text can look suspicious to filters, especially if the image doesn’t load for some reason or the domain has a low sender reputation.
Link shorteners and raw URLs. Shortened links, like ones from bit.ly, are commonly abused by spammers, so filters treat them with more suspicion. Use full, direct links instead.
Recognizable sender name and address. Sending from a generic or unfamiliar-looking address makes subscribers less likely to recognize you, and recognition is part of what keeps you out of spam.
None of these single-handedly sink a campaign (though I saw instances with shortened links), but together they add up, especially on top of an already fragile reputation.
Why this matters more heading into Q4
Sender reputation takes real time to rebuild once it’s been damaged, often weeks, sometimes longer depending on how far it slipped. If your reputation is already shaky heading into November, you’re not just risking one bad send, you’re risking your entire Black Friday sequence landing in spam at the exact moment it matters most.
Checking this now, while a dip in deliverability is a minor annoyance rather than a missed revenue period, is a much better position to be in.
A quick gut check
If any of these feel true right now, it’s worth digging further:
- Your open rates have been quietly declining over several sends, not just one.
- You’ve noticed subscribers mentioning they almost missed your email or found it in a strange folder.
- You recently imported a list from another platform or an old export.
- You haven’t looked at your spam complaint or bounce numbers in months.
Want help figuring out where things actually stand?
Reputation issues are hard to diagnose alone, since the signals live in a few different places and none of them tell the whole story by themselves. If you want a clear read on where your deliverability stands right now, and a plan to strengthen it before your list gets busy for the holidays, that’s exactly what a 1:1 consultation session is for. If there’s a bigger cleanup involved, a Migration and Setup project might be the better fit.
This is post four in Your Summer Email Tune Up. Catch up on domain authentication, domain warming, and low open rates if you missed them.
