[horde] Unable send event notification to attendee

[NAI WEI YEK]

Dear horde list members,

At horde calender, after i create an event and add attendee, i click save
button and it prompt out an error "There was an error sending an event
notification to example at gmail.com: Error connecting to SMTP server." But i
can compose a new email and successfully send the email to recipient in
horde Groupware 5.2.4. Any suggestion to solve this problem?

I'm using Bitnami Horde Groupware Webmail Stack that come along with MySQL
database and Apache web server. In installation I choose Gmail as my mail
server.

Thanks and best regards,
Nai Wei