| Limit |
Value |
Imposed by |
| Rendered signature size |
Under 30,000 characters |
Outlook |
| Image formats |
PNG and JPG. No SVG |
Outlook |
| Image delivery |
Inline cid: attachments, not hosted URLs |
Outlook |
The size limit applies to the HTML, including any footer.
Attached images do not count toward it. A publish that would exceed it is
blocked in the portal.
See Outlook constraints.
| Data |
Retention |
| Template version history |
Last 10 published bodies per template |
| Recently deleted templates |
30 days, then purged by a daily sweep |
| Change log |
Indefinite |
| Signature telemetry |
Indefinite |
| Link click counts |
Indefinite |
| Operator audit log |
Indefinite |
| Change |
Time |
| Template publish |
Seconds |
| Staged publish, for the mailboxes in the slice |
Seconds |
| Promoting or abandoning a staged rollout |
Seconds |
| Version restore |
Seconds |
| Image upload or replacement |
Seconds |
| Footer edit |
Seconds |
| Banner window opening or closing |
Immediately |
| Assignment rules change |
Up to 10 minutes |
| Directory attribute change in Entra |
Within the cache lifetime, without a republish |
| Add-in manifest change |
Requires redeploy, plus 6 to 72 hours propagation and fresh consent |
| Initial add-in deployment |
6 to 72 hours propagation |
Assignment rules are slower than template edits because evaluating a rule needs
directory data, so the per-mailbox result is cached for ten minutes.
| Item |
Value |
| Percentage steps |
10, 25, 50, then everyone |
| Rollouts per template |
One at a time |
| Evaluation frequency |
Every 15 minutes |
| Apply outcomes needed before any decision |
20 on the new version |
| Soak per step |
60 minutes |
| Failure rate that can trigger a rollback |
Above 10% |
| Margin over the current version needed to call it a regression |
5 percentage points |
Both conditions on the last two rows must hold before a rollout is pulled. See
staged rollouts.
| Item |
Value |
| Trial length |
14 days |
| Price |
£0.70 per licensed mailbox per month |
| Billing period |
Monthly |
| Billable seat |
A licensed member mailbox |
| Free |
Shared and resource mailboxes, guests, disabled accounts |
| Seat sync |
Daily, with no mid-cycle proration |
Once a trial ends without an active subscription, signatures stop being served.
See billing.
| Client |
Automatic on compose |
“My signature” pane |
| Outlook on Windows, classic and new |
Yes |
Yes |
| Outlook on the web |
Yes |
Yes |
| Outlook on Mac |
Yes |
Yes |
| Outlook for iOS and Android |
Yes |
No |
Only one event-based add-in runs at a time. If several are deployed, they run
sequentially.
| Item |
Value |
| Read-only impersonation session |
30 minutes, expiring on the server |
| Destructive operator actions |
Require fresh interactive re-authentication |
