When we add New user to our Jira system they are not receiving invitation email.
for example user Akshay More with email id email@example.com
I found that email address you listed was generating a bounce message from the mail server. That error message was:
554 5.4.7 [internal] message timeout (exceeded max time, last transfail: 421 4.4.0 [internal] no mail servers for this domain could be reached at this time)
I have cleared this suppression from our system. You can try to resend invitations.
But that kind of error message is more of an indication that there might be a bigger problem here with your mail configuration. I took a look at your domain's DNS records for mail (MX). It appears that your domain only has a single entry from an MX record. The recommendation is that all domains have at least two entries for MX, in case mail cannot for any reason be delivered to the first entry, the sending mail server can then try to deliver to another mail server. In your case, that cannot happen since there is only a single hostname.
I'd recommend reaching out to your mail administrator if this kind of deliver problem keeps happening.
I tried to lookup the DNS of your mail server. At least from my own machine the results cannot find an IP address of your mail server.
% nslookup mail.synergyinfotech.in
** server can't find mail.synergyinfotech.in: NXDOMAIN
This is most likely the root cause of the problem here. Our mail servers cannot find a valid IP for that host. Hence our email server cannot connect to your email server. I would expect that your mail server would need to be accessible to the internet on a public IP address, so that mail servers can resolve the address of your MX host here.