Deliverability best practices

What deliverability actually means

A delivery receipt tells you one thing: the message reached the recipient’s thread. It does not tell you a person saw it, that the thread stays open, or that your line will still be landing messages next week. Four different outcomes hide behind the word “delivered”:

Queued. Accepted by the API.
Delivered. Landed in the recipient’s thread.
Read. Opened by a human.
Replied. Someone answered.

Deliverability is your ability to keep reaching step 4, across hundreds of conversations, week after week, without a line going quiet. It is a rolling condition, not a per-message result.

curl -X POST https://api.bluereacher.com/functions/v1/messages \
  -H "Authorization: Bearer bluereacher_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "+14155550100",
    "to": "+14155550187",
    "channel": "imessage",
    "content": "Hey Dana, saw you opened the second location last month. Quick question about front desk staffing.",
    "external_id": "camp-q3-0431"
  }'

{
  "external_id": "camp-q3-0431",
  "line_id": "line_9f2c",
  "contact_id": "cnt_88d41a",
  "channel": "imessage",
  "status": "queued",
  "created_at": "2026-07-24T15:04:11Z"
}

A queued status is an acceptance, not an outcome. Judge campaigns on replies. Treat everything before that as a leading indicator.

What you control, what the platform handles

BlueReacher handles	You control
Dedicated iMessage lines, provisioned and managed for you	Who you contact and where the list came from
No A2P registration required to start sending	How many new conversations you start per day
Line health monitoring and alerts on your account	The copy, and how specific it is to the person
Channel fallback to `rcs` or `sms` when a recipient cannot receive iMessage	How fast you answer replies
Send pacing inside the windows you configure	Honoring opt-outs in your own CRM
Opt-out capture on the line	Knowing when to stop

Everything in the left column runs without you. Everything in the right column will sink a campaign if you get it wrong, and no amount of platform-side management compensates for a bad list or a reckless ramp.

Why sending patterns beat message content

Consumer messaging is judged on behavior before anyone reads a word. Three pattern signals carry most of the weight:

Ramp. How fast volume climbs on a line that is new or has been quiet.
Uniformity. How similar your sends look to each other in timing, length, and structure.
Reaction. What recipients do: reply, ignore, block, report.

A well-written message sent 400 times in one hour from a three-day-old line will do worse than an average message sent 40 times across a day. Content still matters, but it matters through humans: better copy earns more replies, and replies are the strongest positive signal you can produce. Pattern rules worth enforcing:

45 to 120 seconds between sends on the same line, randomized. Never a fixed interval.
9:00am to 7:00pm in the recipient’s local time, weekdays.
Vary the opening line across a batch. If 200 messages start with the same six words, that is a pattern.
Keep the first message under 300 characters and put no link in it. Send links after they reply.

Sustainable daily volume

Line age	New conversations per day	Rolling 60-minute cap
Days 1 to 3	15	5
Days 4 to 7	30	8
Week 2	50	12
Week 3	65	15
Week 4 and beyond	80	15

“New conversations” means first messages to people that line has never messaged. Replies inside live threads do not count against these numbers and are not capped. Answer as much as you want. The ceiling exists because consumer messaging is built for people. A person does not open 300 new threads in a day. The further a line’s daily behavior sits from human-plausible, the more it stands out, and standing out is the thing that costs you the line. Scale with lines, not with volume per line. 800 conversations a day is ten mature lines at 80 each. It is never one line at 800. Pushing a single line past its ceiling costs you the line plus the two weeks needed to rebuild that capacity.

Reply rate is your health metric

Reply rate is the only number that reports both things at once: your messages landed, and they landed on people who wanted them.

72-hour reply rate	Read it as
8% and above	Healthy
5% to 8%	Working. Tighten targeting.
2% to 5%	Something is wrong. Diagnose before scaling.
Below 2%	Stop sending on that campaign.

Slice the number per line, per list source, and per day. A pool average of 9% can hide one line sitting at 1%. The comparison that isolates the cause: same copy, same list, two lines. If line A returns 11% and line B returns 3%, the line is the problem. If both fall together, the list or the offer is. Track opt-outs as a share of replies too. Under 5% is normal. Above 10% means you are messaging people who never belonged on the list, and that feeds directly into line health.

List hygiene before a campaign

Do all of this before the first send, not after the reply rate disappoints.

Know the source and the date. Every number traces to a source and a collection date. Anything older than 90 days gets re-verified or dropped.
Normalize to E.164. +14155550187. Strip extensions, punctuation, and duplicated country codes.
Remove landlines and VoIP numbers. They cannot hold a thread and they distort every metric you will use to make decisions.
Dedupe across campaigns, not just inside this one. The same person contacted twice in 30 days from two different lists is your most likely report.
Apply your suppression list on every upload. Past opt-outs, current customers, open conversations, anyone who asked to be left alone. Every time.
Read 25 rows by hand. If you cannot say in one sentence why this specific person would care, the list is wrong. Pacing does not fix a wrong list.
Send a 50-contact test slice first. Wait 24 hours. Read the replies. Then scale.

Step 7 is the one operators skip and the one that saves lines.

Warning signs of degradation

Signal	Usual cause	Act within
One line’s reply rate drops 40% below its own 7-day baseline, same list and copy	Line-level degradation	Same day
Reply rate falls across every line at once	List or offer problem	Pause new sends now
Delivery receipts normal, zero replies across 150+ sends on a line that used to reply	Degradation receipts do not show	Same day
Rising share of “who is this” and “how did you get my number”	Targeting or personalization too thin	Before the next campaign
Opt-outs above 3% of contacts messaged	Bad list source	Stop that source now
More messages falling back to `rcs` or `sms` than usual on a comparable list	Recipient mix, or line-level	24 hours
Read receipts disappearing on a line that used to show them	Early degradation	24 hours

Clean receipts with no replies is the most misread signal in outbound messaging. Delivered is not landed.

The recovery playbook

When a line degrades, run these in order.

Stop new outbound on that line immediately. Do not send a few more to confirm. More sends deepen the hole.
Keep answering live threads. Conversations already in progress are the healthiest traffic you have, and continuing them helps.
Isolate the variable. Two tests, 25 contacts each, 24 hours apart: the same copy on a known-good line, and the same list on a known-good line. One of them tells you whether the fault is the line, the list, or the copy.
Rest the line 72 hours minimum. No new conversations. Replies only.
Re-warm from day one numbers. 15 a day, then 30, then 50. Not from where you stopped. Full recovery takes 10 to 14 days and you cannot shorten it.
Fix the input that caused it. Rest treats the symptom. If you re-warm and go back to the same list at the same volume, you will be here again in two weeks.

If a line fails two re-warms, contact support and ask for a replacement. Two failures means the cause sits with the line, not with how you are sending.

Operating checklist

Daily. Compare reply rate per line against its own 7-day baseline. Clear the reply queue inside 4 business hours. Confirm no line went over its cap. Weekly. Review opt-out rate by list source and retire any source above 3%. Rank lines side by side and flag the bottom one before it fails. Per campaign. Run hygiene steps 1 through 7. Size the campaign to available line capacity before you upload, not after. Set the send window in recipient local time. Reply speed belongs on this list. A reply that sits for six hours is worth far less than one answered in twenty minutes, to the deal and to the line.

Getting started

Integrations

Platform

Deliverability best practices

What deliverability actually means

What you control, what the platform handles

Why sending patterns beat message content

Sustainable daily volume

Reply rate is your health metric

List hygiene before a campaign

Warning signs of degradation

The recovery playbook

Operating checklist

​What deliverability actually means

​What you control, what the platform handles

​Why sending patterns beat message content

​Sustainable daily volume

​Reply rate is your health metric

​List hygiene before a campaign

​Warning signs of degradation

​The recovery playbook

​Operating checklist

What deliverability actually means

What you control, what the platform handles

Why sending patterns beat message content

Sustainable daily volume

Reply rate is your health metric

List hygiene before a campaign

Warning signs of degradation

The recovery playbook

Operating checklist