Connectors → open a mailbox → Details tab
Click a connected email account and stay on the Details tab; scroll to Sending Configuration.
Understand Daily Limit
This is how many emails the mailbox may send per day: a range of 20–500, default 50. New or cold mailboxes should start low.

Decide: auto-adjust or fixed
With Auto-adjust on (the default), FirstSales manages the daily limit nightly from yesterday's Sending health, and the number is read-only. Turn it off to type a fixed limit and click Save.
Set a Send ceiling (optional)
Enter a Send ceiling to cap daily sends: auto-adjust still ramps underneath it but never exceeds it. Leave it blank for no cap. Click Save.
Read the Sending health bar
The 0–100% Sending health score is computed nightly from the prior day's metrics and drives auto-adjust. A low score means the limit gets pulled back automatically.
Check the last auto-adjust
When present, the info popover next to Sending health shows when the limit was last changed and why (tier and reason).
Repeat per mailbox
These settings are per mailbox: set them on every sending account, keeping cold ones conservative and aged ones higher.
Rotate, don't overload
To send more total volume, add mailboxes to the campaign's sender pool rather than pushing one mailbox past a safe limit: see the safe-scaling tutorial.
Pro tips
Leave auto-adjust on and add a ceiling
The safest setup for most users: auto-adjust ramps volume with health, and a Send ceiling stops it climbing past a number you're comfortable with.
Fixed limits are for known-good, aged mailboxes
Turn auto-adjust off only when you have a mailbox with a stable reputation and a volume you already trust.
Watch the health score after warm-up
A dip in the nightly Sending health score is your early warning; auto-adjust will throttle before deliverability tanks: don't override it back up.
More volume = more mailboxes
500/day is the per-mailbox ceiling. Scale by rotating across several senders in the campaign, not by fighting one mailbox's limit.
Frequently asked questions
Where do I set a mailbox's daily limit?
Connectors → open the mailbox → Details tab → Sending Configuration.
What's the range and default?
20 to 500 emails per day, default 50.
What does Auto-adjust do?
It sets the daily limit nightly based on yesterday's Sending health; while it's on, the limit field is read-only.
What is the Send ceiling?
An optional hard cap. Auto-adjust ramps underneath it but never goes above it; leave it blank for no cap.
How is Sending health scored?
Nightly, from the previous day's sending metrics; it drives every auto-adjust decision.
Can I set a limit per campaign instead?
No: the limit is per mailbox. Campaign-level volume comes from how many mailboxes you assign as senders.
Should I raise the limit right after warm-up?
Let auto-adjust do it. A manual jump risks a spam spike; the nightly ramp is safer.
Why did my daily limit change on its own?
Auto-adjust changed it based on Sending health; the info popover shows the exact time and reason.