Gmail ignores period(.) and any random text written after + in email-address ( before @ ). This helps to use same email address for various purposes.

For example, Any of the following email addresses will point to your primary address Exampleorg@gmail.com

Example.org@gmail.com
Example.o.r.g@gmail.com
Ex.ample.org@gmail.com
Exampleorg+randomtext@gmail.com
Example.org@googlemail.com
Example.o.r.g@googlemail.com
Ex.ample.org@googlemail.com
Exampleorg+randomtext@googlemail.com
E.x.a.m.p.l.e.o.r.g@gmail.com

With this trick you can use same email address for work/personal/other category stuff

You can set email id as

Example.org@gmail.com for work
Exampleorg@gmail.com for personal
Exampleorg+othercategory@gmail.com for other category
 
This will help to filter/block incoming email using specified recipient email address.