Why does my integration email say Success but never arrive, skip people, or lose attachments?

Short answer: Send an email has size and recipient limits. Recipients over the limit are skipped while the run still shows success. If nothing was skipped, the email was usually sent and then filtered by the recipient's mailbox.

Why it happens

• An attachment over 10 MB fails ("exceeds the allowable limit of 10 MB" or "request entity too large"), and the email isn't delivered.
• The To field takes up to 40 addresses. Addresses beyond the limit show as skipped.
• The recipient's spam filter or email domain blocks the message.
• The email went to a different address than you expected.

How to fix it

1. Keep attachments at 10 MB or less. Send fewer or smaller files. The Gmail and Microsoft Outlook connectors allow attachments up to 25 MB.
2. Keep recipients within the limit. Use a group or distribution address, or split recipients across several Send an email actions.
3. Open Run history and check the action's output to confirm the right addresses were in To, Cc and Bcc.
4. Ask the recipient to check spam and search the inbox for words from the subject.
5. Use Retest on the action to send to a different address. This shows whether one mailbox or all of them are affected.
6. If Kissflow shows nothing skipped or failed, ask your IT team to check your email domain's filtering. If your account uses a custom SMTP server, Send an email sends through it, so check that server's logs too.
7. For an occasional 500 or internal server error on Send an email, rerun the failed run from Run history. It usually succeeds.