Learn English – Is it “query on ….” or “query about ….”

Depending on the size of the vendor, your assumption may not be entirely warranted. If there are several people who may potentially receive the email at the distributor (as may happen with a shared departmental mailbox) the person who receives your email may not be aware of all the facts.

Accordingly, it may be wise to refer to the previous email at the beginning of your email (..."per the email from Mr. Customer sent yesterday regarding WidgetCo Widgets") and reiterate any key facts that you need to rely upon to make your point (..."we require, as stated previously, forty-two Widgets within a week").

By referring unambiguously to the email at the beginning, you can ensure that the person who receives your email will be reminded (if they had forgotten); will research (if they are a different person who did not initially receive the other email); or will delegate to the appropriate person (if someone else has the responsibility for this transaction).

Even if it is the same person, the phrasing mentioned above should be usable; it never hurts to ensure that your intentions are clear.

Good luck!

With means 'accompanied' or 'by'.

In means 'enclosed' or 'surrounded by'.

Method overloading is calling what appears to be the same function in a program but - because different arguments can be given to the function - it is technically a different method being called. This concept of multiple methods that are the same is known as method overloading.

Varargs is shorthand for 'variable arguments' and is a way of passing a set of arguments to a method without explicitly identifying each individual argument.

Putting it all together:

1) Method overloading can be performed by (using) varargs. So 'method overloading with varargs' is fine.

2) Varargs and method overloading as programming concepts accompany each other. You use different arguments for the same named function in overloading. You provide different arguments to a method with varargs. So 'varargs with method overloading' also works.

3) Method overloading does not need to involve varargs. You can overload a method that takes only one argument instead of a set for instance. These other implementations suggest that conceptually method overloading is larger than, and encompasses, varargs. So 'varargs in method overloading' is correct.

You should not say method overloading in varargs. They can't enclose each other.

I would suggest that all three of the above are perfectly valid. Of them perhaps 2) would generally be less used, but in the context of your question, is absolutely correct.