If you are unable to send an email to a client from a card (there is no "Send from amoCRM" button), make sure:
- You have mailbox integrated in your amoCRM account ("Mail" section);
- The email field is filled in the card;
- The recipient’s email address is correct (there might be an extra character in email address or the address is in Cyrillic). Rewrite the email address over again manually.
If the "Send" button is inactive, make sure:
- The mailbox is synced in your amoCRM account (the "Mail" section);
- The email’s subject, text, the sender/recipient are filled.