Limits and considerations

Every product has edges. This article is the honest, verified list of REDA Connect's — what each channel can carry, how far bulk messaging goes, where opt-out protection reaches, and the one-time org settings some features depend on. Knowing these up front saves debugging time and sets the right expectations with your team.

Channels and message types

SMS is text-only, in both directions. Sending anything but a text message on SMS fails with the error 4. Message type not supported for SMS. on the message record. Incoming SMS that carries media arrives as a failed message with the error Inbound media messages are not supported currently for Twilio. — the media itself is not saved. Pictures, documents, audio and video are WhatsApp features.
Twilio is the SMS provider. The Connect Account's SMS Provider field offers exactly one choice: Twilio. There is no way to connect a different SMS provider in this version.
WhatsApp rich types. Outbound, WhatsApp supports: Text, Image, Document, Video, Location, Interactive - Button, Interactive - List, and WhatsApp Template messages. Inbound, customers can additionally send Audio (voice notes), Sticker and Reaction messages — those three are receive-only; there is no way to send them. The per-channel picture from the agent's view is in What you can send on each channel.

Bulk messaging

Leads and Contacts only. The list-view Send List Message button ships on Lead and Contact — no other object has a bulk path. See Bulk messaging overview.
Use selections of at most 1,000 records. The interface can warn: You have selected more than 1000 records. Only first 1000 records in the list are considered. Retrieval is limited per object configuration. Check the eligible-recipient count before confirming, especially when several configurations match; this warning does not guarantee an aggregate cap.
One opted-out recipient stops the whole send. A bulk send saves all its messages in one all-or-none operation. If any selected person has opted out of the channel, the entire send aborts with the opt-out error (Recipient has opted out of receiving SMS Messages. / Recipient has opted out of receiving WhatsApp Messages.) — no messages are sent, including to recipients who had not opted out. Filter opted-out people out of the list view before sending; see Tracking a bulk send.
Large sends go out one message at a time. After a bulk send is accepted it is processed message by message, so a big batch is delivered over minutes, not instantly. Track progress by the batch subject as described in Tracking a bulk send — a send that is still draining is not stuck.

The Connect Feed

The conversation list is time-windowed — by default it shows conversations with activity in the last 100 days. Older conversations drop off the list but keep their messages, which stay reachable from the record's own page.
The list loads in batches of 100 conversations by default, with a Load more conversations button for the next batch. Both values are adjustable org-wide, within upper bounds — see Feed performance settings.

Keyword choices are fixed. Opt-out keywords can only be STOP and BLOCK; opt-in keywords only START and UNBLOCK. You choose which of them each Connect Account uses, but you cannot add your own words. See How opt-out works.
Opt-out coverage is limited to Leads and Contacts. Both the automatic keyword processing and the block on sending to opted-out people work through a conversation's link to a Lead or Contact. Conversations attached only to other objects (a Case, a custom object) have no automatic opt-out handling — plan your own process there. See Messaging compliance.

Org settings features depend on

Incoming WhatsApp files need a Remote Site Setting. Without it, messages arrive but their attachments never do — a silent failure that looks like a product bug. One-time setup: The Remote Site Setting WhatsApp media needs.
Incoming messages need the public Site. Also one-time, covered in Creating the public Site for incoming messages.

FAQ

It is not configurable. Split larger audiences into selections of at most 1,000, check the eligible-recipient count, and give each batch a separate subject to track it independently.

No. The keyword lists are fixed choices (STOP, BLOCK / START, UNBLOCK). You can still set the opt-out fields on a Lead or Contact manually when someone asks to stop in other words — see Opt-out fields on records.

Bulk sends are all-or-none by design: one opted-out recipient in the selection aborts the entire batch before anything is sent. Exclude opted-out people in the list view filter first.

No. Incoming SMS media is not supported — the message is recorded as failed and the picture is not saved. If customers need to send photos or documents, use WhatsApp.

This article is verified against REDA Connect 1.93. Check the release notes when you upgrade — constraints can change between versions.

Where to go next

Feed performance settings — the adjustable subset of the feed numbers above.
Bulk messaging overview — planning sends within the caps.
How opt-out works — the exact keyword behaviour customers experience.