Field validation/limitation

Field validation/limitation

Hi,

I am new to Zoho CRM.

I would like to limit the entry of certain characters in certain fields and I would also like to receive a notification when importing a contacts in bunch that a certain field does not have the specified format.

If the second thing is not possible, then just limiting characters for some fields would be great too.


I have a single line field where users can type in many email addresses. I would like to set the limit so they can only enter characters typical for email addresses plus commas (because I want those emails to be separated by commas, not space + comma, but just comma without spaces). Here is example of format I would like to achieve:

something@yahoo.com,something@hotmail.com,something@gmail.com


2. How can I set one filed to accept only digits and the characters + and space? Here is example
+12 3456 789


Do I need to create custom function for this and then to create workflow rule that is going to be triggered each time these two fields values are being edited?


Thanks in advance.
The answers will help me to understand field validation better.
If you have some literature or tutorials on these topics, please share it with me. :)