when am executing
|sendemail xxxxx command in search, the job is getting queued and is running forever on one of the search head cluster members.
the is working fine on other cluster members and is sending mail.
email server settings are all same on all cluster members i don't know why
|sendemail is not working on one server.
Are there any errors in the log & can you send email from that search head alone?
Try sending an email via telnet (https://mediatemple.net/community/products/dv/204404584/sending-or-viewing-emails-using-telnet) and see if you get an error. It might be ACL related or with the mail relay.