Sending channels: your mailbox vs. the platform
Last updated July 26, 2026
In short. One-off and sequence emails send through your connected Gmail or Outlook mailbox by default. Pick a verified custom domain in the Send from picker to send that email through SEMAOS from the domain instead. Enrolling a list bigger than your mailbox can send today moves that whole enrollment to your sending domain. Broadcasts always send through the SEMAOS platform.
SEMAOS sends email through two different channels, and knowing which one a given email uses explains most of the product's behavior around limits, tracking, and deliverability. The routing is automatic: one-off emails and sequence steps go through the sending user's connected mailbox, and broadcasts always go through the SEMAOS platform.
Why two channels?
Because 1:1 outreach and bulk mail are different animals, and mixing them hurts both. An email that leaves your own Gmail or Outlook account looks to the recipient's provider exactly like any personal email you wrote by hand, which is the strongest deliverability position a sales email can have. Bulk mail can't ride that channel without burning it: providers cap personal accounts at a few hundred messages a day and get suspicious quickly. So the platform channel absorbs the bulk work on infrastructure built for volume, with its own reputation management.
What routes where?
| Your mailbox | SEMAOS platform | |
|---|---|---|
| One-off emails | Yes, when connected | Fallback |
| Sequence steps | Yes, when connected | Fallback |
| Broadcasts | Never | Always |
| Volume limit | 400 per user per day | Monthly plan pool |
| From address | Your connected address | Platform or custom domain |
| Open/click tracking | Off by default (opt-in) | Always on |
| Replies | Your inbox; auto-detected on Outlook | Reply-To routing |
| Available on Free | Yes | No |
If a sender has no connected mailbox, or the connection hiccups at send time, one-off and sequence sends fall back to the platform channel rather than failing (on paid plans; the Free tier is mailbox-only). A fallback send follows all the platform rules: it counts against the monthly pool and carries tracking.
Can I choose the channel for a sequence or one-off?
Yes, through the Send from address. Leave it on your connected mailbox (the default) and the email sends from your inbox. Pick one of your verified custom domains instead, and it sends from that domain through SEMAOS, with the domain's own warmup and reputation rather than your personal inbox. This is the choice to make when the email should carry a branded address instead of a rep's own.
The picker only offers domains you have verified. The shared platform address is not an option, because a 1:1 email lands better from your own inbox or your own domain than from a shared one. Sequences and one-off sends use the same picker: your connected mailbox is the labeled default, and each verified domain is a separate choice. If you pick a domain still inside its warmup window, the composer shows that day's remaining cap.
What happens if I enroll a list bigger than my mailbox can send?
The whole enrollment moves to the platform channel. When you enroll, SEMAOS compares the list size against what your mailbox has left for the day, which is your 400-per-day cap minus what you have already sent. If the list is larger, every step of that enrollment sends through the platform from your verified sending domain, or from the shared platform domain if you have not verified one of your own. The enroll screen tells you which before you commit.
Say you enroll 2,000 contacts. Your mailbox would need five days to work through them, so SEMAOS sends the list from your domain instead and it goes out in one pass, under that domain's warmup cap.
SEMAOS decides this once, at enrollment, and the choice holds for every step. A contact will not send from your inbox on step one and your domain on step three. Lists that fit inside your remaining budget stay on your mailbox and nothing about them changes.
Free has no platform sending, so an oversized list stays on your mailbox there. The overflow spreads across the following days as your cap resets, and SEMAOS still sends every message rather than discarding the excess.
Which limits apply to which channel?
Mailbox sends are governed by one number: 400 per user per day, with queued work resuming the next day. They are never metered against your monthly plan pool, on any tier. The one exception is a sequence enrollment larger than that day's remaining budget, which moves to the platform channel instead of queueing (see above).
Platform sends are metered against the monthly pool (7,500 on Solo up to 200,000 on Business) and pass the platform's deliverability gates: domain verification, the warmup schedule on a new custom domain, and the bounce-rate guardrails. None of those gates apply to mailbox sends, because that mail rides your own account's standing rather than shared infrastructure.
How do I tell which channel a send used?
The send's detail view shows the channel and the From address it went out with. As a rule of thumb: if the From is your connected mailbox address, it was a mailbox send; if it's your custom domain or the platform domain, it went through the platform.
For the mailbox channel's mechanics (the cap, reply detection, tracking toggles), see connecting your mailbox. For the platform side, see custom sending domains and deliverability.