Mail is arriving with a delay — how often does the inbox refresh?

Senly fetches new mail:

• On every page load of /email (fresh fetch).
• Every 60 seconds in the background (polling) as long as the tab is open.
• Immediately after your own action (send mail, move, archive).

No IMAP-IDLE (real-time push) — that would be too heavy for hundreds of simultaneous sessions. For instant notifications of urgent mail: set up a filter at your provider (Gmail/Outlook) that notifies you via push.