Korumail is not seen in the mail logs sent in version 6.7.2 and the mail does not reach the recipient addresses. Mail sending starts after server restart. But it stops again after 5 minutes.
Korumail version 6.7 and above have new features that requires more resources. So we suggest some of our customers to use 8 GB RAM for Korumail because minumum requirement may not be sufficient for huge traffic.
We request from you to use Korumail with 8 GB RAM firstly and if you have still this same problem, please let us know again and we will investigate your logs to find any probable effects.
Our support guys tried to analyze this situation in our test environment but they did not face anything like this. So that, to identify and resolve your problem they need to access your instance to analyze. Would you send a request about it to our support address: korumailsupport@comodo.com please?