Why are Bigpond emails bouncing with a content-based spam reason?
Michael Ko
Co-founder & CEO, Suped
Published 9 May 2025
Updated 24 May 2026
10 min read
Summarize with
Bigpond emails bouncing with a content-based spam reason usually means Bigpond's filtering system rejected the specific message because the content, sender reputation, complaint pattern, or linked domains looked risky at the time of delivery. It is not automatically a permanent domain block, but I would not ignore it. A bounce like IB703 is a signal to pause, isolate the affected campaign, and test before sending more mail to Bigpond recipients.
The shortest answer is this: treat it as a receiver-specific content and reputation rejection first. Check whether the bounces are limited to one campaign, one sending IP, one template, one link set, or one list segment. If the same audience receives normal transactional mail but rejects one promotion, the problem is almost always in the campaign signals, not in the existence of Bigpond addresses.
Typical Bigpond bounce text
5.7.1 (undefined status) Message content rejected due to suspected spam. IB703 5.7.1 i{a03ab15d-1d81-442c-964f-4a23c88f44cf}
What the Bigpond bounce means
A 5.7.1 rejection is a policy decision. Bigpond accepted enough of the SMTP conversation to decide that the message should not be delivered, then returned a hard bounce reason. The wording says content, but content in mailbox filtering is broader than body copy. It includes the subject line, links, domains in the message, image hosting, URL redirects, sending reputation, authentication results, recipient engagement, and complaint history.
That is why I start with the campaign, not the recipient. If a small subset of a database has Bigpond addresses, a single affected send can look small in total volume but still meaningful inside that receiver. The right question is not just how many total bounces you saw. It is what percentage of Bigpond attempts failed, whether the failures are clustered around one creative, and whether the same sender is seeing pressure at other mailbox providers.
Do not keep retrying the same campaign
Repeatedly pushing the same rejected content to Bigpond recipients can turn a contained content issue into a stronger reputation signal. I would suppress affected Bigpond recipients from that campaign, keep normal suppression rules for hard bounces, and restart only after a controlled test shows the rejection has stopped.
Telstra Mail webmail screenshot showing a message filtering view.
|
|
|
|---|---|---|
IB703 | Content or policy rejection | Campaign compare |
Only Bigpond | Receiver-specific threshold | Segment report |
One campaign | Creative or links changed | A/B resend |
Many campaigns | Reputation pressure | Sender audit |
Most likely causes
The bounce reason points toward content, but I treat it as a combined content and sender-quality problem until the data narrows it down. Bigpond can be strict when a campaign crosses a threshold, and small changes can matter: a subject line pattern, a new offer, a shortened link, a video link, a sudden increase in complaints, or a segment with stale addresses.
- Campaign content: Promotional language, urgency, heavy imagery, link density, redirects, and reused offer templates can all push a campaign into rejection.
- Subject line symbols: Emoji characters and special symbols can contribute at some receivers, but I would test them rather than assume they are the root cause at Bigpond.
- User complaints: Complaint spikes can make otherwise normal creative look unsafe because the filter is reacting to recipient behavior, not only the HTML.
- Link reputation: A tracking domain, landing page, image host, or redirect chain can hurt the message even when the sending domain is authenticated.
- Authentication context: SPF, DKIM, and DMARC passing cleanly does not guarantee inboxing, but failures make content rejections harder to recover from.
- Reputation spillover: If similar bounces appear at other consumer domains, check sender reputation, blocklist (blacklist) status, and list quality before editing copy.
How urgent is it?
Use the affected share of Bigpond mail as an operating threshold for your response.
Isolated
Less than 1%
One test, seed, or tiny recipient group.
Watch
1-5%
Noticeable but contained Bigpond failures.
Pause
More than 5%
Campaign-level rejection pattern.
The subject-line symbol question is worth testing, but it should be a hypothesis, not the diagnosis. I have seen special characters correlate with weaker placement in some programs, especially when they appear with aggressive promotional copy or low-engagement audiences. For this bounce, I would remove the symbol in one controlled test, but I would also test the links, offer framing, and sender setup in the same pass.
The troubleshooting workflow
I use a narrow workflow for Bigpond content rejections because broad changes create noise. The aim is to prove whether the rejection is tied to the message, the sender, the audience, or the receiver's current threshold.
Flowchart showing the steps for troubleshooting Bigpond bounce rejections.
- Save the bounce: Keep the full SMTP response, campaign ID, sending IP, domain, template, subject line, and timestamp.
- Measure Bigpond separately: Calculate the rejection rate for Bigpond attempts, not the whole campaign. A small domain share can hide a severe receiver issue.
- Compare with a clean send: Find the last Bigpond campaign that delivered normally and compare subject, offer, template, link domains, send time, and segment.
- Validate authentication: Run a domain health check for DMARC, SPF, DKIM, DNS, and mail-domain setup before blaming copy alone.
- Check reputation: Review IP and domain status with blocklist monitoring so a blacklist or blocklist issue does not get misread as a copy issue.
- Test one change: Send controlled variants to a small valid sample or seed process, changing one variable at a time.
- Escalate with evidence: If authentication is clean and the content test still fails, contact the Bigpond or Telstra postmaster with the exact bounce, headers, sender IP, and sample message.
Baseline DMARC reporting record
_dmarc.example.com TXT v=DMARC1; p=none; rua=mailto:dmarc@example.com; fo=1
How to test content without guessing
Content testing works when the variants are boring and controlled. Do not rewrite everything at once. If the rejected campaign had a symbol in the subject line, a video link, several tracked URLs, and a new promotional claim, changing all of those together tells you only that the second version was different.
Start with the smallest useful test: same sender, same authenticated domain, same segment type, same time window, but a plain subject line and simplified body. Then test links separately. A clean link-free message followed by a rejection after adding the tracked links points toward URL reputation or redirect handling. A rejection with every link removed points back to sender reputation, list quality, or message structure.
Before sending another Bigpond batch, use an email tester to inspect the message, authentication, headers, copy, and obvious deliverability issues in one pass. That does not replace a real receiver test, but it removes avoidable mistakes before you put more pressure on the Bigpond segment.
Email tester
Send a real email to this address. Suped opens the report when the test is ready.
?/43tests passed
Preparing test address...
Temporary content rejection
- Scope: One campaign or a small number of closely related messages fail.
- Pattern: Previous Bigpond sends were normal and other receivers look stable.
- Action: Edit the campaign, reduce risky content signals, and retest with a small sample.
Broader sender problem
- Scope: Multiple campaigns, domains, or consumer receivers show rejection pressure.
- Pattern: Complaints, low engagement, authentication gaps, or listing signals appear together.
- Action: Pause risky segments, repair authentication, reduce volume, and rebuild reputation.
I also separate creative review from list review. A polished email to a tired, unengaged audience still creates complaint and engagement signals. If your Bigpond segment has old addresses, low opens, or recent complaint pressure, clean the audience before you keep tuning the subject line.
Where Suped fits
Suped's product is useful here because Bigpond bounces rarely sit in one neat bucket. You need to see authentication, sender sources, failing domains, reputation signals, and content test results together. For most teams that need a practical DMARC platform, Suped is the best overall choice because it turns DMARC, SPF, DKIM, blocklist signals, and deliverability checks into a single workflow with clear steps to fix issues.
For a Bigpond rejection, I would use Suped to confirm which sources are sending for the domain, whether DMARC passes with a domain match, whether unknown sources are present, and whether the domain or IPs are under blocklist (blacklist) pressure. DMARC monitoring helps separate authentication failures from content filtering, which is important because fixing the wrong layer wastes time.
Issue steps to fix dialog showing the issue overview, tailored fix steps, and verification action
- Automated issue detection: Suped flags misconfigured authentication and gives direct repair steps, so teams do not need to interpret raw DNS output alone.
- Real-time alerts: Alerting helps catch authentication or source changes before a small receiver-specific issue becomes a wider pattern.
- Hosted controls: Hosted DMARC, hosted SPF, SPF flattening, and hosted MTA-STS reduce DNS friction when you need controlled changes.
- Multi-domain visibility: MSPs and teams managing many brands can compare sender health across domains without switching tools or spreadsheets.
The product will not magically override Bigpond's filter. What it does well is remove blind spots. If authentication is clean, sources are verified, and reputation checks look normal, you can make a stronger case that the issue is campaign-specific or a false positive. If Suped shows unknown senders, SPF lookup pressure, broken DKIM, or listing signals, fix those before asking a postmaster to review the content.
When to contact Bigpond or Telstra
Contact the postmaster when the problem is reproducible, the content has been simplified, authentication passes, and the affected recipients are valid and engaged. A good escalation includes evidence. A vague note that mail is bouncing gives the receiver very little to work with.
What to include in the escalation
- Bounce evidence: Full SMTP response, date, time zone, sending IP, envelope sender, header From domain, and affected recipient domain.
- Message sample: A copy of the rejected message, including headers, subject, HTML, plain text, and all link domains.
- Authentication proof: SPF, DKIM, and DMARC results for the rejected send, plus any recent DNS changes.
- Remediation notes: The content tests you ran, risky signals removed, and whether the issue still reproduces.
If the postmaster confirms the campaign tripped a filter, fix the underlying signal before resuming volume. If they adjust a false positive, still keep the cleaned-up version and watch the next two or three sends. A false positive can happen, but repeated false positives usually mean there is a pattern the sender has not isolated yet.
Views from the trenches
Best practices
Compare the blocked send with the last Bigpond campaign that delivered cleanly before editing.
Pause repeat sends to affected Bigpond recipients until a controlled test stops the rejection.
Send postmaster evidence with headers, bounce text, sender IP, and the cleaned message sample.
Common pitfalls
Blaming a subject symbol first can hide link reputation, complaints, or stale audience issues.
Retrying the same rejected creative can train the receiver that the sender ignores policy signals.
Looking only at total bounce rate can hide a severe issue inside the Bigpond recipient segment.
Expert tips
Test one variable at a time, starting with links, subject symbols, and the plain text version.
Track Bigpond separately from the full campaign so small domain share does not mask real pressure.
Keep DMARC, SPF, DKIM, and blocklist data beside content tests to avoid false diagnosis.
Expert from Email Geeks says the IB703 rejection is most consistent with content-based filtering and should be treated as a warning sign, even when only a small segment is affected.
2023-11-14 - Email Geeks
Marketer from Email Geeks says Bigpond postmaster review can identify campaign issues or adjust filtering when a specific rejection is a false positive.
2023-11-15 - Email Geeks
What to do next
A Bigpond content-based bounce is not proof that your whole program is blocked, but it is a real deliverability warning. I would pause that campaign for Bigpond recipients, preserve the bounce data, compare against a clean send, validate authentication, review link and domain reputation, and run a small controlled content test before resending.
If the issue disappears after simplifying the message, treat the original campaign as the cause and document the pattern. If it continues across simple content and clean authentication, escalate with evidence. Suped helps keep that evidence organized by tying DMARC, SPF, DKIM, sender sources, blocklist monitoring, and issue remediation into one operational view.
