Unfortunately, yes – this is common practice. That does NOT make it acceptable, however. Call your broker with the paperwork in front of you and go over it. Do not sign ANYTHING that you do not understand.
Depending upon how real estate agency works in your area, there may be parts where he or she is supposed to advise you and parts where he or she is not. Is this broker also representing the seller, or is this a ‘Buyer’s Broker" representing you, exclusively?
I highly recommend that you consult an independent real estate attorney as well. A real estate transaction is extremely important, extremely expensive, and has the capacity to end disastrously if it is not laid out correctly. The small cost of an attorney as compared to the high risk of not having one should make the fee a non-issue. Shop around and ask friends and family for references.
Your question can be best answered by breaking it up into multiple parts.
Part 1: Is it common practice for a real estate broker to mail/e-mail paperwork to you for your signature? Yes. Regardless of the type of transaction(s) you’re involved with, your broker is going to need you to review and sign documents. The documents, depending on the transaction, may include, but are in no way limited to, contracts, disclosures, leases, purchase and sale agreements, etc. The most common real estate transactions involving individual consumers include buying a home, selling a home, and renting or leasing a home (as either the tenant or the landlord).
Part 2: As mentioned in Part 1, the documents provided to you (from your broker) are for you to review and sign. From the second part of your question, “…with no one to explain what it is you are signing?” This is where the answer changes to, No. First of all, you should read any document to determine what it is before signing it. If you read something that you don’t understand, or otherwise have questions about its content or meaning(s), then you shouldn’t sign it until such a time as you understand and agree with the document contents.
If your broker ever extended an invitation for you to ask questions, then you should take him/her up on that invitation. If you don’t remember if this was ever verbalized to you, and if it was never given to you in written form, then this question isn’t for this forum – it should be directed to your broker. Your broker is the professional in the transaction and should be relied upon in all respects applicable to the transaction – that’s why they’re being paid. If you ever question their competence or integrity, then get a second opinion by speaking with another professional, including another broker, or an attorney qualified in the area of real estate applicable to your transaction.
Part 3: Your next line gives further indication that your broker may not have indicated (in writing) that you do anything other than sign the documents and return them. Regardless if this is the case, you need to understand the documents you are signing. If you haven’t read them, you should do so. If you’ve read them, still have questions, have asked your broker for assistance to no avail, then you may want to consider finding a broker who can and will explain the documents to you. Remember that your broker is a professional and not an attorney. If you are seeking legal advise regarding the documents or the transaction, you should certainly contact an attorney qualified in the area of real estate applicable to your transaction.