The number one request is that you send your list in MS Word format. I know, I know, Excel is so easy and convenient but which would you rather look at if you had to sit down for several hours to address envelopes? This:
Or This??:
That's what I thought. {The correct answer just to be clear is option 2} Just to explain, when you send your list in Excel, the addresses are written ACROSS the page and they are all very close together. This makes it very easy to put the wrong address with the wrong guest or the wrong zip code with the wrong address. You get the picture. But when your addresses are in word, they are so neatly stacked on top of each other, just as you would write the addresses out. {No cheating and copy/pasting your list into Word, that's still a spreadsheet and it defeats the purpose of having the list in Word.}
If you already have your addresses laid out in Excel, it is very simple to do a mail merge. In the tools drop down menu on the toolbar in Word there is a function listed under Letters and Mailings called Mail Merge Wizard that will walk you through an easy mail merge.
Once your list is in Word, the next step is to number it. Frequently, there are additions and corrections to the list after the fact. It is extremely time consuming to have to read through every name on the list to find the guest address that needs correcting. If your lists are numbered and alphabetized, it makes this a snap and we can certainly take care of it for you.
Finally, write your list EXACTLY as you want to see it written on the envelopes. If you want everything spelled out formally, then do not abbreviate state names, street, avenue, etc. {there are some words it is considered "appropriate" to abbreviate, you should inquire with your calligrapher if you have questions}. Why is this important? Because when your calligrapher looks at an envelope he/she determines the spacing of each line in their head. If you abbreviate California, it may throw the last line off balance from the top two lines. I tend to look at the second line in relation to where the first line is and the third in relation to the second. That is why it is so important to spell out everything. This also leaves absolutely no room for interpretation, discrepancies, confusion, and misunderstanding. {This is also why some calligraphers charge more for centering, because it takes longer to write each envelope if you have to figure out the spacing first} 
Just remember, your calligrapher is performing a service for you, and it is impossible for him/her to complete their job to the best of their abilities if you do not supply them with the proper tools. Each calligrapher has their own set of policies in place that they have determined will help them deliver the most gorgeous possible product. It is also possible that if you submit your list incorrectly you will be asked to resubmit the list, so it's best to just do it right the first time. For that reason, please take the time to read the contracts you are signing and familiarize yourself with the policies.
