Once your site is listed in dmoz.org do you have to re-submit every once in a while like other search engines?

Hi Michael - No need - once you're in you'll stay in. Actually there is no need to re-submit to any SE once you are in. HTH

There is no need to submit more than once to anything, before or after listing.

Repeated submissions get tagged as spam eventually.

Your talking about all search engines. I have search engine submission software and the various engines allow you to resubmit after a certain period such as 30, 60, or 90 days. So I thought if you stay within that time frame then your site won't be considered as spamming. I have seen many search engine submission sites that say something like the following:
1.) Re-submitting helps your site maintain better placement on the engines. With many search engines and directories new registrations get precedence over older registrations. By re-submitting your site it will help maintain better position since the search engines get millions of submissions each day.
2.) Resubmitting your URL once a month is not spamming. Spamming is when you submit multiple copies of the same or similar pages. We have not had any complaints from the search engines for the method we use of submitting monthly and it is actually encouraged by many to help them keep their database up to date.

Are the 2 reasons to re-submit above true?

3.) Search engines lose entries and purge their database periodically. By re-submitting your page monthly you insure that your site will remain in the database and it helps keep your listings up to date as you make changes to your site. Even if the first 2 above aren't true this 3rd reason should be valid since it would take to much time to check every search engine to make sure.

I thought all of this was true, especially the first one. When I would not submit a site for a long time it seemed like the traffic would go down and would go up a few months after submitting again.

Lets distinguish between search engines and directories.

1) That might have been true some time ago, but as you could read on several boards it isn't any more. meanwhile search engines discovered, that the prople resubmitting are mostly the same people spamming.

2) Thats right for search engines. Thats wrong for firectories. SEs don't have additional work by resubmissions, directories have. In a directory, someone has to remove your additional submission - if you resubmit on a regular basis, the person doing that might find it annoying and thatfor is tempted to remove your site. "Spamming" a directory is not the same for a searchengine.

3) Thats not true any more, if it ever was. They spider sites in their database on a regular basis to catch updates - while doing that they spider new sites, too. You wont get any bonus by resubmitting, at least with the big players. If your site has been down for a longer period the SE might take this as "no longer exists" and you wouzld have to resubmit - but if you trake google as the most relevant SE, it would follow the inbound linmks to your sites again and find it without you doing anything.

So better look if you can find your site in the specified SE/directory and if _not_ then resubmit.

Once your site is listed, there is never a reason to resubmit to ANY search engine, and there is only a need to resubmit to a Directory if there is a major change to your web site that requires a new title or description. In that case, you should not resubmit, but rather use the change request form that most directories have.