Symptoms
While trying to open Webmail, this error is shown:
"Service Unavailable". The corresponding service is not available at the moment, trying it withing 2-3 minutes. For more information please contact your service provider." is shown.
At the same time /var/log/httpd_error_log.ssl on the Webmail server shows
Allowed memory size of 52428800 bytes exhausted (tried to allocate 1048576 bytes)
Cause
Low Apache memory limit prevents Webmail from opening correctly.
Resolution
Modify the below values in webmail.conf
[root@webmail ~]# grep memory_limit `/usr/local/pem/etc/apache/webmail.conf`
php_admin_value memory_limit 150M
php_admin_value memory_limit 150M
Then restart the Apache service to apply the changes:
# /usr/local/pem/etc/apache/pemhttpd.init restart