When you are served with a lawsuit, it is always in your best interest to respond to the lawsuit papers by filing an Answer with the Court. If the papers were sent to your address, then the Court will have a record of that. If you do not respond, the lawsuit could result in a Default against you, which would mean that you could have a Judgment entered against you, and find future problems such as your bank account being restrained (held) or other judgment enforcement issues. By Answering the lawsuit, you have the ability to tell your side of the dispute. I would not ignore the lawsuit due to a minor defect in the papers; but, you could address that when you do go to court. If it is de-minimus (small) defect, the Court may just allow the suing party to amend the papers anyway, so to protect your rights, go to the Court and file your Answer to the papers. Do not delay, as you only have a short amount of time to file the Answer. Check with the Court in your jurisdiction for that time frame.
First the laws and rules of each state can vary quite a bit. That being said, generally, it is never a good idea to ignore civil process papers when they are served on you personally, or on any person over age 18 at your primary residence. Depending on the state law where you reside, the personal service may be sufficient to require your answer or response to the complaint. Although there are circumstances where lack of personal jurisdiction or invalid process defenses can be asserted, these are generally subject to correction.
Depending on the nature of the proceeding, the court involved, and your status, some states and in some instances federal bankruptcy courts permit service of process by certified US Mail. Again, if your defense is something technical as in a misspelled name, but the process used was reasonably intended and did actually give you notice of the existence and nature of the claim, most states laws will permit the case to move forward, with you or without you.
Many other issues can arise, however, like statutes of limitation, technical requirements of state law, and prospects of seeking to response a default judgment if one is obtained against you. For this reason, its best not to assume you can easily ignore the suit without seeking the advice of a skilled attorney in your state or jurisdiction.
Note: This Answer and any information contained in this answer is not intended to be treated as legal advice, but is offered solely for information purposes; And, this posting does not create an attorney-client relationship or privacy privilege of any kind. This attorney licensed only in Georgia.