Originally Posted by MedsenFey
It is not normal for most meads to develop sulfur odors.
When you have hydrogen sulfide develop, if it is left alone, it may form mercaptans and later disulfides which cannot be easily removed. It is best to get rid of sulfur odors as soon as possible. Since fermentation is finished, I'd splash rack it once and if it still stinks, I'd consider treating with copper.
I read on Jack Keller's site that splash racking helps wines with H2S. I haven't done it myself with meads, but would be the way to go. From Jack Keller's site:
How to Treat Hydrogen-Sulphide
Hydrogen sulfide does much more than impart off-smells and flavors to wine. Hydrogen sulfide can be detected by smell in quantities as low as 2 parts per billion. It can usually be dissipated during the first 2-3 weeks after its production begins by racking and aerating the wine. After several weeks, it tends to react with other components in the wine to form less volatile mercaptans, which themselves can be further oxidized to disulfides. These latter compounds are almost impossible to remove from wine by stripping methods, and their presence in the wine makes it undrinkable. Both mercaptans and disulfides have a notable skunk-like smell.
Hydrogen sulfide is usually formed after fermentation has concluded and detected when the wine is racked. If the hydrogen sulfide has not sat in the wine too long, it can be treated with a maximum measure of 0.5 ppm of copper, the amount contained in 0.75 ml of a 1% solution of copper sulfate pentahydrate added to a gallon of wine. The hydrogen sulfide should be gone within two days and the wine can be treated normally. However, it will take about 3 rackings, 20-30 days apart, to remove all excess copper from the wine. If not removed, the copper itself can taint the wine.
The amounts of copper sulfate pentahydrate used are so small, and the risks to fatally damaging the wine by adding too much are so real, that it is impractical to treat small amounts (less than 5 gallons) of wine. The preferred treatment is still to add sulfur dioxide in the form of potassium metabisulfite solution (see Measuring Additives in Winemaking) and then rack the wine with plenty of aeration to drive off the H2S.
A proprietary compound called Sulfex can also be used to treat hydrogen sulfide formation. It comes as a 10% slurry in water and is added to wine at the rate of 0.5-5 grams per gallon. It is insoluble and settles out without leaving any traces in the wine if subsequently racked properly at least twice. I have never used it but have heard it works well.