When using Gmail with multiple accounts, should each account have a spam filter?

Question

I currently have Gmail set up to read mail from several different accounts, most of them are other Gmail accounts. I'm wondering what the best way to set up the spam filters for these accounts is. Do I set up the spam filter on each individual account, or bypass the spam filter on each of these accounts and only enable it on the main account?

It's my understanding that Gmail uses (at least something similar to) Bayesian filtering, where it will learn from the messages you mark as spam. My email accounts are set up so that they get a similar email. So for example, I have a personal account, a work account, and one that I use to signup for services.

I'm not sure if the spam filter is smart enough to also look at the to field for its algorithm. If it was, then I think the obvious choice is to use a single spam filter on the main account.

Use a spam filter on the main account only:

• Pro: There's only one spam box to check for false positives.
• Con: Might degrade the spam filtering logic since now it's getting a bunch of different types of email messages.

Use a spam filter on each individual account:

• Pro: Might improve spam filtering logic since each email address is going to get a similar mail.
• Con: If someone tells me they sent me a message and I don't see it, I have to log in to that account and manually check the spam filter.

Which method would you recommend? (Did I make any false assumptions? Any other pros/cons?)

Answer 1

I would let one account handle the spam filtering for all of your accounts. I don't believe there are many benefits to having each account handle its own spam. I think Gmail is aware of the destination address of each incoming mail and having identical spam emails (with only the destination address changing) will strengthen the spam algorithm just as much as if it were single emails sent to multiple accounts.

Regardless of how much (more) it might improve the spam algorithm, you should choose the solution which best improves your workflow. I would just go with the first option (spam filter on the main account).

FYI: I use Gmail to process email from 12 accounts across 7 domains each with spam being primarily handled by my main Gmail account. :)