In Administration > Configuration there are a number of configuration values.

key	default	meaning	availabe since OpenMeetings version
user.login.minimum.length	4	minimum chars required for the login to create a user	1.9.x
user.pass.minimum.length	4	minimum chars required for the password to create a user	1.9.x
number.minutes.reminder.send	15	minutes the one-time reminder in the calender is send, set to 0 to disable reminder	1.9.x
max_upload_size	1073741824	Maximum size of upload file (bytes) 1073741824 bytes = 1GB	1.8.x
show.whiteboard.draw.status	0	Display name of the user who draw the current object (User Name auto-disapper after 3 seconds.	1.8.x
use.old.style.ffmpeg.map.option	0	If the system should "." (old ffmpeg) instead of ":" (new ffmpeg) for the -map option in FFMPEG	1.9.x
inviter.email.as.replyto	1	Set inviter's email address as ReplyTo in email invitations (1 == set, 0 == NOT set)	2.0.x
office.path		The path to OpenOffice/LibreOffice (optional) please set this to the real path in case jodconverter is unable to find OpenOffice/LibreOffice installation automatically	2.0.x
default.landing.zone	dashboard.rooms	Area to be shown to the user after login. Possible values are: dashboard.rooms, dashboard.chat, calendar, rooms.public, rooms.private, rooms.user	2.1.x
sms.provider		SMS service provider (bulksms.http.1)	2.1.x
sms.Username		Login for SMS service provider	2.1.x
sms.Userpass		Password for SMS service provider	2.1.x
sms.subject		Subject of SMS reminder message	2.1.x
swftools_zoom	100	DPI for conversion of PDF to SWF (should be an integer between 50 and 600 with a default value of 100 DPI)	2.0.x
swftools_jpegquality	85	Compression quality for conversion of PDF to SWF (should be an integer between 1 and 100, with a default value of 85)	2.0.x
sendEmailAtRegister	0	User get a EMail with their Account data. Values: 0(No) or 1(Yes)	2.0.x
sendEmailWithVerficationCode	0	User must activate their account by clicking on the activation-link in the registering Email. Values: 0(No) or 1(Yes) It makes no sense to make this(sendEmailWithVerficationCode) 1(Yes) while sendEmailAtRegister is 0(No) cause you need to send a EMail.	2.0.x
redirect.url.for.external.users		Users entered the room via invitationHash or secureHash will be redirected to this URL on connection lost	2.2.x
allow_frontend_register	(configurable during install)	Is user register available on login screen	1.8.x
allow.soap.register	1	Is user register available via SOAP/REST	3.0.x