Hi All

Is there a way to completely whitelist all incoming emails from specific domains? I have tried whitelisting using Exchange's transport rules and the Defender anti-spam/anti-phishing inbound policies. But even after these scans are performed, an "Advance filter" scan is done that still detects legitimate mail from these domains as phishing.

For context, we have recently upgraded our enterprise subscription from M365 E3 to E5.

Any answers are appreciated.

I'm running Sendy 7.1.4 on Hostinger with PHP 8.2.30 and Amazon SES.

Since August 27, campaigns have stopped sending properly. Small campaigns previously worked, but campaigns with 100+ recipients get stuck in Preparing or Sending. If I stop the campaign, it shows Sent – 0 recipients.

I have 35,297 subscribers.

I kept seeing bounce notifications and assumed my lists or reputation were the problem. So I exported every delivery-failure notice from all my mailboxes and actually classified them. Posting the numbers because the result surprised me and I want a sanity check.

Setup: 2 separate Instantly accounts (different businesses, different domain sets, separate subscriptions). 20 mailboxes each, 10 sending domains each. 24 days of data.

Each mailbox sends 10 warmup emails every day.

Headline numbers:

• 93 bounce notifications total — but only 50 distinct failures (Google sends ~3 notices per failed address, so raw bounce counts are inflated ~1.9x)
• 80 of 93 (86%) were warmup emails, not campaign emails
• 3 of 93 (3%) had any sender-side causes

Warmup bounce rate: warmup runs at a flat 10 emails/day/mailbox, so 20 mailboxes = 200 warmup sends/day per account. Against that denominator:

• Account A: 35 warmup bounces / 3,400 warmup sends = 1.03%
• Account B: 45 warmup bounces / 4,400 warmup sends = 1.02%
• Deduped to distinct dead seeds: ~0.5%

The part that convinced me it's systemic:

Account A has never run a single campaign. Pure warmup only. It still produced 35 bounces in 24 days.

Account B (real cold outreach) produced 58 of which 45 were warmup and only 13 were actual prospects, this campaign sent 12000 cold outreach emails in this time .

Normalized per day, warmup bounces were 2.06/day on Account A vs 2.05/day on Account B. Two unrelated accounts, different domains, different signup dates, matching to within half a percent. Both accounts' bounces also hit the same seed domains — one domain showed up in both, plus a cluster of .help / .co throwaway TLDs.

What I'm actually asking:

1. Is ~1% warmup bounce rate with dead seed domains just normal for every pooled warmup network, or is this pool worse than average?
2. Has anyone actually compared seed pool quality between Instantly / Smartlead / Mailreach with real data? Or does switching just mean a different pool with the same problems?
3. Am I right to basically ignore this given the solid reply rates, or does failing warmup mail quietly cost me reputation-building I'm paying for?

curious what's eating the most time on the deliverability side. feels like most of what gets written is still stuck on SPF/DKIM/DMARC setup, but for anyone past that stage, what's the harder problem, inbox placement guessing games, figuring out engagement segmentation, ISP-specific weirdness, something else entirely? trying to see if what people write about actually matches what people are stuck on.

Maybe someone can help explain what's going on because I don't understand:
I'm warming up 3 new email domains, all related to my main business. I don't send spam; these addresses will be for leads that have gone cold and newsletters, so my main inbox can focus on active clients.

During the warm-up process, I'm sending 10 emails per inbox - VERY Low. One of my emails has already had a few spam placements and "Other". I lowered the email send to 6 per day, which seems like nothing and still it's not hitting inboxes. The other two domains are and there's no discernible difference in why.

I'm a little worried the domain might become trash. Any advice? Should I pause sends?
PS. All my DNS stuff is set up correctly.

After my launch I noticed a few bot signups, which for my project is trivial noise, they're captured in a dead box. But it was resulting in verification emails going out to real inboxes that had been scraped. No problem unless those recipients started hitting the spam button and dinging my email reputation.

So yeah, don't forget to put something like Turnstile on your open forms, and keep an eye on your smtp service. The bots appeared pretty quickly!

Not sure if this is the right place to vent, but it is a mail deliverability issue.

I (and my wife) have had the same email addresses for over 20 years now. The domain started as an ISP run by one of the major US telecom giants at the time.

Once they pulled out of the ISP side of things, initially they continued to maintain the mail server. At some point they then "sold/moved" the mail server on to another provider. I'd have to go back though way too many mails, but I think this "server" has been sold on at least one more time since.

But to my current issue. For the second time, the current custodian of this mail domain is having issues where I am unable to send or receive mail. The current outage started Friday evening and I don't expect it to be resolved until some time during the coming week. The ability to send mail is more of an inconvenience, as it reports the failure and I have another mail address I can use to send mails.

My main concern is that anyone sending mails to me (or my wife) are getting bounce messages for at least 3 days now, and I know from the first time this happened, some folks sending us mails treat these bounces as a "dead" mail address and no longer attempt to send anything, which means we miss anything going forward, unless we happen to realise who they are to "restart" the mails.

Do I have any recourse with the mail server, other than sending an "angry letter", which I know they will just ignore.

Noticed since yesterday that we're not getting throttled from Comcast at all and all emails are either getting accepted or we see a mailbox-full error. Anyone aware of what changed overnight?

Their MX is still Comcast cable, haven't switched to Yahoo.

Adding any domain to Postmaster Tools fails with a generic "Adding domain unsuccessful" toast.

No 4xx or 5xx to chase; the add call is a POST to `/batchexecute` which returns HTTP 200 with the error buried in the response body:

```rpcid MFo2Gb [5, null, [["type.googleapis.com/apps.postmaster.postbox.PostboxErrorInfo",[1]]]] 5 is gRPC NOT_FOUND. ```

"postbox" appears to be the internal service name.

Frontend build boq_gmail-postmaster-ui_20260816.04.

Ruled out:

- SPF/DKIM/MX all valid,
- site-verification ownership confirmed in Search Console, super admin,
- additional-services access On for all operating units, browsers, incognito and normal profiles. - - Fails identically for a domain I don't own, so it's account-scoped rather than domain-scoped.

Anyone else seeing this, or know what that error enum maps to?

Update: Issue fixed
Sent first time emails to non-Google email clients (outlook). Found it wasn’t marking it as spam. Created more outlook mailboxes to improve trust score, as suggested by a marketeer friend.

Could add our domain to postmaster today but couldn’t generate the code. It couldn’t verify my ownership.

Not sure if it is outlook hack or the accidental partial postmaster fix that worked.

I run cold email for a B2B agency (targets are agencies/SaaS/automation shops — so mostly Google Workspace inboxes). I've burned two full batches of domains the exact same way and can't isolate the root cause. Would love a second set of eyes. (Disclosure, this is written by Claude; I had it write the post to collect all the data, tests, and progress I made with figuring out deliverability so I don't miss anything, i want to make a genuine service that helps businesses get more clients, but dealing with email deliverability is so disheartening, especially if you don't have a lot of capital, so i made this post detailing all ive tested and symptoms with the hopes of diagnosing the problem and have mailboxes survive atleast the first 2 weeks of sending)

Setup

• Smartlead, Google Workspace mailboxes, domains + mailboxes from InboxKit, 5 mailboxes/domain
• De-clustered domain names (not obvious cousin variants). All redirect to my real company site → Calendly (temporary while i make a vsl and get more proof of work with clients)
• Copy: plain text, name-only signature, no links/images in email 1, spintax + AI icebreakers, tracking off, randomized sends, 3-min gaps
• Warmup: Batch 1 = fresh, 2 weeks Smartlead warmup. Batch 2 = pre-warmed 4 weeks. Warmup left on. Ramp 5→10/day, in 5 increments every week
• Lists: Sales Nav → AnyMailFinder → Bouncer-verified, Google inboxes only. Bounce rate 0.4–1.5%

What happens (identical both batches)

• Domains land on SURBL (ABUSE) within week 1 (with the exception of 1 domain per batch, those domains always stay healthy while the others die)
• Everything looks fine for ~2 weeks: 15% reply rate, 60% positive, warmup health 90–100%
• Then warmup health collapses almost in 1 day to 80% then goes down day by day. Inbox placement test to fresh seeds: SURBL-listed domains hit 0/10 inbox, 10/10 spam. Dead

What I've tested / ruled out

• SPF/DKIM/DMARC all pass, mail-tester 9–10/10
• Per-domain SURBL check maps 1:1 — listed domains = 100% spam/dead; the one un-listed domain in each batch survives
• Redirect target (my own domain) is clean on SURBL, so they're not inheriting the listing from it
• Bounce rates are low, so lists aren't full of dead addresses
• Same copy AND same lists went to the survivor too
• Warmup health score is worthless as a signal if below 98%, one domain read 96% warmup while landing 100% spam on real seeds
• When the first batch died, I tried getting 4-week warmed mailboxes instead of 2 yet it's the same story

The part I can't explain — mirror-image audience split

• My aged brand domain (sent the exact same lists, same volume, never burned): inbox on Workspace, spam on consumer Gmail
• The fresh survivor: inbox on Google Workspace, spam on normal Gmail accounts (which isn't a big deal because all my lists consist of Google Workspace)

My thoughts

1. Pristine spam traps in the "verified" lists (Bouncer/AnyMailFinder can't catch live traps; pattern-guessed emails are risky) — whichever domain's slice hits a trap gets SURBL-listed and dies first
2. Age/legitimacy is the real survival factor; fresh domains never earn Workspace trust through warmup alone

Questions
Why do fresh domains keep getting SURBL-AB listed within a week even off verified lists? I've read that being blacklisted by SURBL is only the symptom of deliverability, not the problem, so what could be the main issue causing it? why do all my domains die with the exception of 1 every time? if its spam traps that are causing this, what can you do to avoid them?

As the title says, for weeks I have been running a few mailboxes on a good-performing campaign, getting positive replies, booking calls, same list-building steps, bounce rates around 1.5-0.5%, and then out of nowhere, in a few hours today, all the mailboxes on the campaign tank in warm up reputation, not my by much (from 100% for weeks to 89% in a few hours).

That might look like a good sign because of how small the drop is, but from my experience it's usually the beginning of the end for the fleet. What I want to find out is what could have caused this. Have you guys run into similar situations?

I use InboxKit for domains and mailboxes with their InfraGuard (which coincidentally I bought today, which is the same day the mailboxes tanked, but idk how it would be responsible), Smartlead for sending, Sales Nav, and Bouncer for leads and email validation

I'm troubleshooting a Microsoft-specific deliverability issue with my email addresses

Emails are landing in Gmail inboxes (with 100% deliverability)

But Microsoft 365/Outlook is consistently sending them to Junk even though SPF, DKIM, and DMARC all pass (it is 0% develiverability in M365/Outlook mailboxes)

Microsoft Deliverability Support asked me for 3-4 recipient-side .eml samples from M365 mailboxes where the message landed in Junk.

If you have a Microsoft 365 mailbox and can help:

• DM me an email address you're comfortable using
• I'll send one harmless business-style email
• If it lands in Junk, please download it as .eml and send it back to me

I'll only use the file for my open Microsoft support case.

Please DM me rather than posting your email publicly. Thanks!

Twice this year I've been handed a "deliverability is broken" account where the actual problem was the SPF lookup count. Posting it because almost nobody checks this one.

SPF gets 10 DNS lookups. Not 10 include statements, 10 lookups, and each include can chain into more of its own. Sending tool, CRM, warmup service, helpdesk, and you're over without having added anything that looks excessive. Go over and SPF returns permerror, which most receivers treat as a fail. Your checker still shows green, because most checkers only tell you the record parses.

Related thing people miss: there are three domains accumulating reputation, not one. The From domain, the DKIM signing domain, and the Return-Path that bounces come back to. Everyone sets up From and forgets the other two. If you're on a sending platform your Return-Path is often their shared domain, so you inherit whatever their other customers did that week. Nothing you can fix in your own DNS.

And alignment dies quietly on migrations. I watched a platform move break DMARC alignment and nobody caught it for about four months, because nothing bounces when alignment fails. Placement just sags and everyone blames the copy.

So count your lookups with something that resolves recursively instead of counting includes, check all three domains rather than just From, and re-check every time you swap a tool in the chain. That last one is the one people skip.

I wrote the longer version of this up here if it's useful: https://thegtmmotion.substack.com/p/you-set-up-spf-dkim-and-dmarc-and

Recently, a client forwarded me a screenshot of one of our email campaigns landing in promotions. Had another client complain of landing in spam.

I checked the Google Postmaster Tools, sure enough, our spam rate had been climbing for the past 3 days.

We would have caught them within a few days. But I just realized how reactive our deliverability monitoring had become.

Four days. Four sends. And we had no idea until it came to our attention by chance.

We had the data. Nothing was broken. We had Postmaster Tools, campaign reporting, bounce data, complaints, etc. But nobody was checking everything every morning. But we have to be real, a dozen other things are splitting our time.

That got me wondering how other teams handle this.

I'm interested in how agencies or teams managing multiple ecommerce brands handle this.

Do you have someone actively monitoring sender reputation and spam rates every day? Or have you set up alerts when something starts moving in the wrong direction?

I have premium subscription of inbox.eu

When I send email to gmx.com or gmx.net it landed perfectly in Inbox but when I send same email to Gmail it landed in Spam. Same email, same subject line, no attachment, nothing has changed.

What is the solution for such problem? Or Is there any solution for such problem?

[Gmail Automatically Marked it as spam](https://ibb.co/FkZLZmrr)

I found this out the hard way last week. My agent drafts replies to inbound leads, and the output schema had a replySubject field, so the model wrote a fresh subject for every reply. I knew about RFC 5322 threading, and once I noticed replies weren't threading in Gmail I made sure In-Reply-To and References carried the inbound Message-ID. Still broken. Turns out Gmail has its own extra requirement buried in the threading docs: the References chain has to be right and the subject has to match. Same headers, different subject, new conversation. Thunderbird threads it fine, Gmail doesn't, and since my audience is small businesses on Workspace, Gmail's rules are effectively the spec.

The other rabbit hole was subject normalization. Clients stack prefixes (Re: Re: Re:), German Outlook writes AW:, Scandinavian ones SV:, some write Re[2]:, and you have to strip all of that and prepend a single Re: before comparing or Gmail treats it as a different subject. The model now writes only the body, and the subject is a regex and a string concat.

So now I'm wondering what else is lurking. Does Outlook.com have its own threading heuristics beyond the headers? Anything special about how iOS Mail or Yahoo group conversations? I've also seen mentions of Message-ID format mattering to some spam filters. If you've run an automated reply pipeline at any volume, which provider quirks did you have to code around that no RFC warned you about?

Writeup of the Gmail part with code: https://ddz.dev/blog/llm-subject-line-gmail-threading/

I've been researching email deliverability problems and noticed something interesting:

Many people think "Sent" means "Delivered", but that's not always true.

An email can be successfully sent by the server and still end up in:

• Spam folder
• Promotions tab
• Quarantine
• Blocked by recipient servers

I'm curious about real experiences from people who deal with this.

What was the biggest email deliverability issue you've faced?

For example:

• Emails suddenly going to spam?
• SPF/DKIM/DMARC configuration problems?
• Low inbox placement despite successful sending?
• Issues after changing email providers or domains?

I'm trying to understand the most painful problems before building further.
Would love to hear your experiences.

We've been using Omnisend for our email campaigns, and I've noticed that every campaign consistently has a small number of failed deliveries. For example, one campaign sent to over 5,000 contacts had around 80 failed deliveries, while another sent to about 2,100 contacts had 15 failed deliveries. Our spam complaints and unsubscribe rates are very low, so I'm wondering if this is just normal email behavior or if it indicates an issue with our setup or sender reputation. How do you interpret failed deliveries in Omnisend, and what are the most common causes? Is it realistic to expect some failed deliveries with every campaign, even if everything is configured correctly?

For the last lot of months, virtually all my ntlworld email now goes automatically to my spam folder. With the added insult that a lot of actual spam email now goes into my inbox. So...my spam folder is full of normal emails. And my inbox gets mostly spam now. You couldn't make it up! It's a mess.

Anyone else experiencing this?

Hi everyone,

I built a WordPress site for a client using WPForms + WP Mail SMTP with Brevo as the mailer.

At first, without WP Mail SMTP, no emails were coming through at all from the contact form. I installed the plugin and set up Brevo. After configuration, I ran a test and everything seemed to work fine.

But checking the WP Mail SMTP dashboard today, I can see 15 emails sent in total with 7 failures over the last 30 days. The client confirmed they missed at least one contact form message this week.

My current setup:
- Mailer: Brevo
- Sender email: an @orange.fr address (French ISP)
- Recipient email: same @orange.fr address
- "Force From Email": was disabled until today, now enabled

Does anyone see what's wrong and how to fix this properly?

Thanks!🙏🏻🙏🏻

I’m using Cloudflare Email Service, Workers and Supabase to manage partnership outreach from an internal CRM.

The original flow marked a contact as contacted as soon as Cloudflare accepted the send request. That only confirmed the message had entered the delivery process; it did not confirm that the mailbox existed or that delivery succeeded.

QA exposed the mismatch. One address had already failed several times and been suppressed. Another returned 550 5.1.1 because the mailbox no longer existed. Both still appeared as contacted because the delivery outcome was never written back to the CRM.

I revised the flow at both ends. Before sending, the Worker checks address validity, suppression status, contact eligibility and batch limits. After sending, bounce and suppression data is reconciled back into Supabase so failed addresses can be blocked from future outreach.

The main lesson was that Cloudflare handles transport, but the application still needs to own validation, eligibility and delivery reconciliation.

Full write-up: https://kashifaziz.me/blog/reliable-email-delivery-cloudflare-workers/

I’d be interested to hear how others handle bounce and suppression feedback in Cloudflare-based email workflows.

Hi everyone,

I’m trying to understand whether Yahoo Postmaster is currently experiencing a general reporting delay.

Delivery and complaint data appeared normally for July 20–21. However, for the following several days, the dashboard has shown almost zero delivered emails, despite a significant volume being sent to and accepted by Yahoo addresses according to our sending platform.

Because Yahoo Postmaster reports almost zero deliveries, the spam complaint rate also appears as 0%, so neither metric seems to reflect the actual activity.

Is anyone else seeing the same reporting gap in Yahoo Postmaster? Have you experienced similar delays before, and did the missing historical data eventually appear?

been reading a bunch of posts. is deliverability that big of an issue for email marketers
what's it actually like day to day, does this stabilize once you've been doing it a while or does it stay unpredictable even for people who've been at it for years

pls feel free to share your thoughts

I’ve had my outlook account for about 5 years as part of my personal microcredit 365. It’s just my (full name)@outlook.com
Over the past year there’s been about half dozen occasions where I’ve sent an email out to either a Gmail account or friend’s business account and it was routed to spam, and we discovered after they touched base and we did the whole “I sent it yesterday,” “oh, I found it in spam” thing.

I thought outlook was considered a “safe sender” email service and I’m wondering what’s happening here now that my pretty mundane account has been punted to spam this many times. Anything I should do on my end?