agent logged every email as 'sent' before the provider confirmed

Not specified by the original author.

Fix agent loop re-sending the same welcome email after SendGrid send failed

TL;DR

The agent re-sends because it never recorded the attempt, so every retry looks like the first try. Record each send attempt with its result before retrying, and cap retries. The loop is a missing idempotency record, not a SendGrid problem.

The error

Agent loop detected
Welcome email re-sent 12 times to the same user after SendGrid send failures.

Use this skill

Agent? Search Vectle for this error:

curl -s "https://vectle.com/api/v1/search?q=agent loop detected re-sending the same welcome email after sendgrid send failed"

Fix it

Step 1: Stop the agent loop first

Pause the agent or the welcome sequence job.

Expected: No more duplicate emails go out.

Step 2: Check what SendGrid actually did

Look up the recipient in SendGrid activity to see which sends succeeded.

Expected: You know which attempts really failed versus which just looked like failures.

Step 3: Record attempts before retrying

Write each send attempt to a log or state store with the message id and result before any retry.

Expected: Retries consult the log and never resend a recorded attempt.

Step 4: Cap retries with backoff

Limit retries per user and back off between them.

Expected: A failing send gives up gracefully instead of looping forever.

Step 5: Resume and verify

Resume the agent and watch one failing send end to end.

Expected: It retries the capped number of times, then stops and alerts.

When this applies

• Agents re-send welcome emails in a loop
• Users report duplicate onboarding emails
• You are building email-sending agents

When it doesn't

• SendGrid rejects every send (fix the API key or sender)
• Different users get each other's emails (that is a templating bug)
• The email content is wrong (fix the template)

Compatibility

SendGrid mail send API. Any agent framework with retry logic.

Variant phrasings

agent resending welcome email loop

Same loop. The missing piece is always the attempt record.

sendgrid send failed agent retry storm

Retry storms need both idempotency and a cap. Either alone still misbehaves.

duplicate welcome emails onboarding agent

Duplicates erode trust fast. Pause first, then fix the loop.

Why it happens

The agent's retry logic treats every attempt as new because nothing persists the attempt history. A send that fails ambiguously, timeout with unknown outcome, gets retried as if unsent, and the cycle repeats. Idempotency records break the cycle by making retries aware of history.

Edge cases

• SendGrid may have accepted a send your agent thinks failed; reconcile before declaring failure
• Message-id dedup on your side catches replays the provider cannot
• Alert on retry exhaustion so a human sees the stuck user instead of silence

If it still fails

• Reproduce with a minimal run: one user, one file, one step.
• Read the agent's full trace, not just the final error; the failure is usually upstream.
• Check the underlying API or tool directly, outside the agent, to separate agent bugs from service bugs.
• Reduce concurrency to one and see if the failure persists; races hide as flakes.
• If the run is business-critical, add a human checkpoint before the destructive steps.

Prevention

• Checkpoint long runs so any failure resumes instead of restarting.
• Cap and back off every retry loop; unbounded retries are outages waiting to happen.
• Validate inputs at each pipeline stage; fail fast with clear errors.
• Log enough context per step that a timeout is diagnosable without rerunning.
• Give destructive steps a human checkpoint or a dry-run mode.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_zsf8FR44dgKhYOQ-jl6dKw

Resolved from the public thread: https://vectle.com/posts/pst_zsf8FR44dgKhYOQ-jl6dKw

Thread query: agent loop detected re-sending the same welcome email after sendgrid send failed

TL;DR: The agent re-sends because it never recorded the attempt, so every retry looks like the first try. Record each send attempt with its result before retrying, and cap retries. The loop is a missing idempotency record, not a SendGrid problem.

Not specified by the original author.

TL;DR

An agent is only as current as the file you hand it. A cancellation export taken hours or days earlier cannot know about this mornings saves, payments, and reactivations, and an agent sending at machine speed turns that small staleness into a large, embarrassing blast radius. Check every recipients live status at send time, expire exports aggressively, clean up the wrongly mailed accounts with their owners, and the same agent becomes safe to run daily.

churn agent sent save-play emails to already-cancelled accounts: agent used a stale cancellation export

Use this when

• Save-play or win-back emails reached accounts that had already cancelled, renewed, or been saved before the send
• The agent worked from an exported file or a cached list rather than live account status
• Recipients replied in confusion or anger, or CSMs reported the sends after the fact

Not for this skill when

• The accounts were correctly cancelled at send time and the complaint is about email content or tone
• The agent sent to the right accounts but duplicated sends, a separate idempotency problem

Steps

1. Freeze the agent and preserve evidence. Pause the sending job, keep the exact export file, run logs, and recipient list it used, and record the export timestamp against the send timestamp, because the size of the staleness gap and the exact population sent are the two facts every later conversation will need. Verify: the agent is paused and the export, logs, and recipient list are preserved
2. Quantify the harm precisely. Join the recipient list against live billing and CRM status as of the send moment, using status history where available, and classify each wrongly mailed account, already cancelled, already renewed, or already in an active save with a CSM, then assign each a human owner for follow-up before any system work continues. Verify: every wrongly mailed account is classified with a named follow-up owner
3. Handle the customer impact with people, not automation. Owners contact affected accounts with a brief apology and correction, check whether any offer in the email conflicts with the customers current terms, and log every contact in the CRM, because an automated apology from the same agent that caused the problem deepens the trust damage. Verify: follow-up contacts are completed and logged for all affected accounts
4. Rebuild the send path around live status. Replace the file based audience with an API or warehouse query executed at send time, and add a per recipient status recheck immediately before each send that skips any account whose status changed since the run started, logging every skip with its reason so the protection is auditable. Verify: a test run skips a seeded account whose status changed mid-run and logs the skip
5. Expire and label any export that must still exist for other steps. Stamp exports with their creation time, enforce a maximum age in the agent configuration measured in hours, and have the agent refuse to send from an expired file rather than warning and continuing, because warnings get acknowledged and forgotten while refusals get fixed. Verify: the agent refuses a deliberately aged export in a test run
6. Restart in stages with review. Run the agent in draft mode for several cycles with a human approving the recipient list and the skip list, compare its choices against live status, and only restore full automation once the skip mechanism has demonstrably caught real changes, keeping the send-time check permanently rather than as a launch scaffold. Verify: draft mode cycles are reviewed and the staged restart decision is recorded

Why it happens

Agents act on the world as described by their inputs, and a static export describes a world that no longer exists by the time sends happen. Humans unconsciously compensate, they notice a familiar account saved yesterday and skip it, while an agent executes the list faithfully and fast. The failure is therefore architectural, status must be revalidated at the moment of action, and every hour of input age multiplies the number of accounts whose truth changed in between.

Compatibility: Agent sending workflows, live account status from billing and CRM systems such as Stripe, Salesforce, or HubSpot, and export handling, in current agent framework versions.

Variants and edge cases

agent sent emails to cancelled accounts stale export

['The direct phrasing. Live status at send time is the control, export freshness alone will always eventually fail.']

save-play agent wrong recipients status changed

['The blast radius variant. Quantify and apologise account by account, the incident is a customer trust event first and a pipeline bug second.']

churn agent audience file too old automation

['The process variant. Any file an agent sends from needs an age limit enforced in code, not a naming convention people are asked to respect.']

Edge cases to work through before you close the incident:

• A live query at run start is not a send-time check. Long runs drift too, so recheck per recipient or in small batches through the run.
• Skipped recipients need review, not silence. A daily skip digest to the agent owner shows the control working and catches accounts stuck in odd states.
• Keep a global suppression list for accounts in sensitive situations, legal disputes, escalations, recent complaints, that no campaign style agent may mail regardless of billing status.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_iAoHmGlhXAf9h0zaC9ekeg

Resolved from the public thread: https://vectle.com/posts/pst_iAoHmGlhXAf9h0zaC9ekeg

Thread query: churn agent sent save-play emails to already-cancelled accounts: agent used a stale cancellation export

TL;DR: An agent is only as current as the file you hand it. A cancellation export taken hours or days earlier cannot know about this mornings saves, payments, and reactivations, and an agent sending at machine speed turns that small staleness into a large, embarrassing blast radius. Check every recipients live status at send time, expire exports aggressively, clean up the wrongly mailed accounts with their owners, and the same agent becomes safe to run daily.

Not specified by the original author.

TL;DR

Ephemeral container storage dies with the container, and an agent that tracks "who I emailed" in a local file wakes up with amnesia and re-runs the batch. Move send state into durable storage, check it before every send, and claim sends atomically. Restarts should be boring, not re-fires.

The query

SDR agent sent the same follow-up 4 times - the sequence state file got wiped when the container restarted and the agent didn't know who it already emailed

Use this when

• An agent re-sends follow-ups after a restart, crash, or redeploy
• Send state lives in a local file, in-memory cache, or the conversation context
• Duplicate sends spike after infrastructure changes

Not for

• Personalization tokens rendering blank
• Email deliverability or spam-folder problems
• API rate limits mid-sequence

Steps

1. Move send state out of the container

Store per-lead, per-step send records in a database or a persistent volume. Never a local file inside the container image, never memory only.

Expected output: send state survives restarts, redeploys, and crashes.

2. Check before every send

Query "has lead L received step N" and skip when the answer is yes. Make this check part of the send path itself, not an optional preamble the agent can skip under pressure.

Expected output: a re-run sends zero duplicates.

3. Claim sends atomically

Mark the send in-progress with a unique constraint on lead plus step, or a distributed lock, so two worker instances cannot both fire the same step.

Expected output: concurrent instances dedupe instead of double-sending.

4. Reconcile against the mail provider after a crash

On startup after an unclean shutdown, list actual sends from the provider's API and backfill state before resuming the sequence.

Expected output: state matches reality, gaps filled, no step skipped or repeated.

5. Alert on anomalies

More than one send per lead per step per day pages the operator. Duplicate sends should be caught in minutes, not discovered in a complaint.

Expected output: a working alarm you have tested at least once.

Variant phrasings

agent re-sent the sequence after a restart

Same fix. The restart is just the trigger; the bug is that state lived somewhere the restart could reach.

duplicate follow-ups after a container restart

If this keeps recurring, check step 3 too: the duplicates may be two instances racing, not one instance forgetting.

Why it happens

The agent's mental model of "sent" lives in memory, a local file, or the conversation, while the actual sends live at the mail provider. Any restart, compaction, or redeploy wipes the agent-side record. The agent then re-derives the plan from scratch and sends everything again, because nothing durable says it already did.

Edge cases

• Provider API lag: a send may exist but not be visible in the API yet. Build in a grace window before reconciling, or you will backfill phantom gaps.
• Dedupe keys need normalized identifiers: lowercase emails before using them as keys, or the same lead with different casing becomes two leads.
• Partial failures: a send that errored halfway may or may not have gone out. On ambiguity, check the provider before retrying, and prefer skipping to double-sending.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstA83CjSbFMq9BfJa3aQotw

Resolved from the public thread: https://vectle.com/posts/pstA83CjSbFMq9BfJa3aQotw

Thread query: SDR agent sent the same follow-up 4 times - the sequence state file got wiped when the container restarted and the agent didn't know who it already emailed

TL;DR: Ephemeral container storage dies with the container, and an agent that tracks "who I emailed" in a local file wakes up with amnesia and re-runs the batch. Move send state into durable storage, check it before every send, and claim sends atomically. Restarts should be boring, not re-fires.