The following error appears in mail_nxd.log after upgrading Service Desk Manager 17.x:

Failed to send mail. Reason: javax.mail.SendFailedException:

Failed to send the mail after trying with all the mail hosts

The Mail NXD options are empty in NX.env but shows up as installed in the application.

Release : 17.2

Component : SERVICE DESK MANAGER

1. Go to Administration > Options Manager > Email

2. Confirm that the mail nxd  are installed and not empty:

example:
MAIL_SMTP_HOSTS
MAIL_SMTP_DOMAIN_NAME
MAIL_FROM_ADDRESS
MAIL_REPLY_TO_ADDRESS

3. Go to NX.env and confirm the same options from above are empty:

example:

NX_MAIL_SMTP_HOSTS=
NX_MAIL_SMTP_DOMAIN_NAME=
NX_MAIL_FROM_ADDRESS=
NX_MAIL_REPLY_TO_ADDRESS= 

4. Re-install the options at application level > Restart Services

If AA environment : Restart STBY > Failover STBY > Failover BG > Restart application servers.